XNA Creators site kindly kept everyone informed here
http://creators.xna.com/en-US/news/xnags40beta

And if you want to get straight into the action go here http://creators.xna.com/en-US/launchcenter and hit the big download link.
Make sure to read the release notes as there's some fairly crucial changes in there if you've been using an older version.

Perhaps this might be a good time to start thinking of a tutorial/sample you can share with others using the new WP7 Beta.
http://www.sgtconker.com/2010/07/teaser-xna-tutorial-contest/

The main blog post from the WP7 dev team is Windows Phone Developer Tools CTP Refresh! and gives a great basic overview. If you want to get straight to the bits, that link is Windows Phone Developer Tools CTP - April Refresh. You will want to pay attention to the Release Notes this release as there are breaking changes if you have any projects created in the first CTP. There is also an overview of what has changed on MSDN, What's New in Windows Phone 7 CTP Refresh.

If you followed my post about Ultimate support (Windows Phone 7 Installation User Errors With Visual Studio 2010 Ultimate RC), there are a couple of caveats to uninstalling the RC bits. You may run into more problems when trying to install the CTP Refresh so hopefully this will help eliminate some headache ahead of time.

1. Do not uninstall individual pieces like XNA or heaven forbid Visual Studio 2010 Express. The installer keeps track of everything it puts on your system and will proceed to add it back if it is missing. In the case of no VS2010, as The_Zman found out the hard way and had to reinstall the Express RC separate.
2. The CTP leaves two things that the refresh needs to be removed before it will install: Silverlight 4 SDK and Microsoft Visual Studio 2010 Express Prerequisites x86 or x64 depending on your system.
3. I had a link to the Silverlight 4 Tools that have now been refreshed to RTM. That link is actually no longer needed as VS2010 RTM installs them for you.

Hope this reiteration will save some of you the grief The_Zman or ElementCy ran into. Happy hax0rin!

In this article I will explain how to use the Push Notification features of Windows Phone 7 using 2 very simple samples.

The push notification features of Windows Phone 7 enable you to push a message to a mobile device with 3 options.

• Tile notification – This lets you change the main application tile on the Start experience.
• Toast notification – This lets you popup a message on the device even if your application is not running.
• Raw notification – This lets you send raw data to the running application which you can receive via an event.

For this sample, we’re going to concentrate on Toast notification. While Tile notifications will be cool, we unfortunately can’t make use of them with the current build of the emulator.

As a teaser, here is the result we want.

A toast notification contains 2 text properties. These could be considered as a header and details. The toast notification also shows the icon from the application on the left hand side.

There are 2 parts to this sample. The first is the WP7 application itself. This must first open a communication channel with the soap service and bind the notification to a toast. Firstly we can try to find an existing channel and if that fails, we open a new one.
Once opened, we call the BindToShellNotification method on the channel so that the result ends up as an actual Toast notification.

Here’s some sample code.

channel = HttpNotificationChannel.Find(channelName);
if (channel != null)
{
    Debug.WriteLine(channel.ChannelUri.ToString());
}
else
{
    channel = new HttpNotificationChannel(channelName);
    channel.ChannelUriUpdated += new EventHandler<NotificationChannelUriEventArgs>(channel_ChannelUriUpdated);
    channel.Open();
    channel.BindToShellNotification();
}

Once we’ve found a channel or created a new one, we need to retrieve the unique URL generated for this communication. In this sample we will simply print it out to the debug console. Later in the article I will explain a real world scenario for how this type of communication may be used.

Subscribe to the ChannelUriUpdated event and print out the Url.

channel.ChannelUriUpdated += new EventHandler<NotificationChannelUriEventArgs>(channel_ChannelUriUpdated);
void channel_ChannelUriUpdated(object sender, NotificationChannelUriEventArgs e)
{
    Debug.WriteLine(e.ChannelUri);
}

That’s all we need in the WP7 sample code to show you how notifications work. In short, the WP7 application doesn’t have to do much at all. Once the channel is successfully created that is enough for the device to receive a toast notification.

Now we need a way of sending a push notification to the device.

To do this we need to send a HTTP POST method to the Url given by the WP7 device application. You will find this in the output window of Visual Studio

We need to add a custom header to set the notification class and we also need to fill up the payload with some specially formatted data so that the toast will be received.

The format of this data should be as follows. [NOTE: The MSDN documentation is not correct, notice where I put the xmlns and also where I use the X-NotificationClass header]

X-WindowsPhone-Target: toast

<?xml version="1.0" encoding="utf-8" ?>
    <wp:PushNotification xmlns:wp="WindowsPhonePushNotification">
        <wp:Toast>
            <wp:Text1>{0}</wp:Text1>
            <wp:Text2>{1}</wp:Text2>
        </wp:Toast>
    </wp:PushNotification>

Replacing the {0} and {1} with the data you want to show on the device.

A couple of things to be aware of here. There must be a blank line between the X-WindowsPhone-Target and the xml. Also, this format contradicts the documentation on MSDN. The documentation is wrong for all formats.

Here is how I get this payload ready in code.

    string ToastPushXML = "X-WindowsPhone-Target: toast\r\n\r\n" +
                "<?xml version='1.0' encoding='utf-8'?>" +
                "<wp:PushNotification xmlns:wp='WindowsPhonePushNotification'>" +
                    "<wp:Toast>" +
                        "<wp:Text1>{0}</wp:Text1>" +
                        "<wp:Text2>{1}</wp:Text2>" +
                    "</wp:Toast>" +
                "</wp:PushNotification>";

    string str = string.Format(ToastPushXML, textBox2.Text, textBox3.Text);

We also need to convert this to a byte array so we can fill the HTTP Request.

Here’s the complete code to send the notification.

    string ToastPushXML = "X-WindowsPhone-Target: toast\r\n\r\n" +
                "<?xml version='1.0' encoding='utf-8'?>" +
                "<wp:PushNotification xmlns:wp='WindowsPhonePushNotification'>" +
                    "<wp:Toast>" +
                        "<wp:Text1>{0}</wp:Text1>" +
                        "<wp:Text2>{1}</wp:Text2>" +
                    "</wp:Toast>" +
                "</wp:PushNotification>";
    string url = [URL GIVEN BY WP7 APP];

    string str = string.Format(ToastPushXML, textBox2.Text, textBox3.Text);

    HttpWebRequest sendNotificationRequest = (HttpWebRequest)WebRequest.Create(url);

    sendNotificationRequest.Method = "POST";
    sendNotificationRequest.Headers = new WebHeaderCollection();
    sendNotificationRequest.ContentType = "text/xml";

    sendNotificationRequest.Headers.Add("X-NotificationClass", "2"); //- 2/12/22 are for toasts

    byte[] strBytes = new UTF8Encoding().GetBytes(str);
    sendNotificationRequest.ContentLength = strBytes.Length;
    using (Stream requestStream = sendNotificationRequest.GetRequestStream())
    {
        requestStream.Write(strBytes, 0, strBytes.Length);
    }

If we now run the WP7 application, we will see the URL appear in the Debug output window. Select and copy this complete URL.

Now put this URL into the test push application, enter some text in the 2 fields and press the push button.

With a bit of luck the cloud service will be responsive and you will receive the toast notification on the device almost instantly. I was told by someone at Microsoft that these are subject to delays depending on how busy the service is at that time. That’s ok though, it’s understood that Push notifications are not a guaranteed form of communication anyway, they’re just cool.

The source code shown above was purely to give you an idea on how to use this. Download the full source code sample at the bottom of this article.

One thing to be aware of with the WP7 device application is that it may error on trying to open a channel on the first few tries. I’ve not figured out why this is yet, but just keep trying and once it succeeds once, it should succeed from there on out.

Real World Scenario

Here’s a real world scenario on why you may use Toast push notifications.

I’m playing a game with my good friend X-Tatic, we’re playing WP7 Battle Ships. I’ve just take out his small boat when I need to check my emails and diary and make a phone call.

So I exit the game and get back to work on my device. At this point, the application will open a communication channel, or if it did it previously in the app, we just make a note of the URL we got created and send this to the WP7 Battle Ship server. The Server will store this so that if it needs to send a toast to this user/device, this is the URL it will use.
While I’m reading my truck load of emails I suddenly see a toast notification popup.

At this point I’m like… UH!! WAH!! WTF!!! So I hit the toast, it fires up WP7 Battleships taking me right back into the game we were playing and I proceed to sink the rest of X-Tatics ships.

There are many many more useful scenarios for this and I would love to see and hear about them. Please keep Sgt. Conker informed of any cool things you do with Windows Phone 7 Push Notifications.

Download Sample

References
Push Notifications Overview
How to: Set Up a Notification Channel
How to: Send a Push Notification

There’s no perfect “one size fits all” answer to help you make the choice for what is best for your game, so you’ll want to think about the tools you want to use, and the type of experience you want to enable when approaching developing your game.

In the Windows Phone Developer Tools Preview you’ll find:

• Visual Studio 2010 Express for Windows Phone
• Windows Phone 7 Series Add-in for Visual Studio, for developers already working with Visual Studio 2010 RC1
• Windows Phone 7 Series emulator
• XNA Game Studio 4.0

Demo [Harvest, developed by Luma Arcade] looks awesome, full 3D, animating characters. More will be shown at MIX next week.

The game loop on the phone is similar to existing platforms, but tweaked for power efficiency.

The phone graphics is an evolution of the existing immediate mode rendering API, 2D and 3D:

• New configurable effects: BasicEffect, SkinnedEffect, EnvironmentMapEffect, DualTextureEffect, AlphaTestEffect
• Custom programmable shaders are not supported on the phone
• Image scaler:
  • lets you render to any size backbuffer, and have this automatically scaled to fill the screen
  • lets the same game run on both 800x480 and 480x320 display sizes without special coding
  • provides automatic rotation to support portrait, landscape left, and landscape right modes
  • the image scaler is free: it uses dedicated hardware so does not consume any GPU

Portability: the ability to target three screens. Portability lets you target more sockets with a smaller time investment. Portability is not just about the same game running on different platforms, it is also valuable to share infrastructure, knowledge, etc.

Framework feature profiles:

• Reach: broad base of devices including phones
• HiDef: Windows and Xbox only

“Focus on being a game developer, not plumbing the underlying technology”

“Michael Klucher plugs forums.xna.com, says our MVP's are awesome and do a great job answering questions.”

“Michael Klucher gets applause!”

The will be more talk about the Marketplace and the Windows Phone emulator at the MIX next week.

XACT is part of the HiDef feature profile, so not on the phone: use SoundEffect (+ 4.0 enhancements) on the phone.

Ozymandias has an article about how to get in touch with Microsoft to get access to Xbox LIVE on the phone.

Update (2010-03-11 02:31 GMT): The Shawn has another blog post up, high-level-detailing some Windows Phone support related work done.