Catalin on 2D Skeletal Animations
Catalin “Too Proud To Self-promote” Zima (you might know him as our local XNA MVP Captain ZSquare) has a nice write-up of 2D Skeletal Animations over at his blog. So, if you ever wondered what the benefits of skeletal animations in the 2D world as compared to our beloved sprite sheets are, his post would be your starting point to explore this very topic.
Screen-space deformations in XNA for Windows Phone 7
Captain ZSquare shares his technique to do screen-space deformations on Windows Phone 7. Introduces Catalin:
Working on our games, we came across the need to do some screen-space deformations for all sorts of special effects like explosions, ‘drunk filter’, warp effects and other similar stuff. But since we’re targeting Windows Phone 7, we don’t have access to any custom shaders (which is a bummer), so we had to be creative. In the end, the solution turned out to be rather simple, and the performance is good enough (if you don’t go overboard with the effects, of course).
See the post for screen shoots and code!
Lets see if Captain ZSquare reposts this one with a screen shoot, too 
Article: Arbitrarily Shaped Secondary 2D Viewports
by Harry Trautmann
This tutorial shows a technique to implement a secondary 2D viewport which has a shape that does not need to be rectangular, but can be customized by the programmer. Even moving sprite shapes are possible. Utilized code techniques: secondary rendertarget (of XNA Game Studio 3.1) and an alphamap by a pixelshader (PS 2.0).
This tutorial is for beginner to intermediate level programmers. At least you should know the oo basics and know the nitty-gritty about the XNA framework. Also, basic shader programming is explained somewhere else (e. g. here: http://www.sgtconker.com/2009/11/crash-course-in-hlsl/)
Article: XNA Farseer Platform Physics Tutorial
by Roy Triesscheijn
Today I’m going to introduce you to a neat 2D physics engine for XNA called Farseer. With the help of this 2D physics engine we are going to create a small platform ‘game’ while introducing the important concepts of Farseer like bodies, geometry, joints and springs.
By the end of the tutorial, you'll be able to build something like:
Article: Rolling World Tutorial
by Christian Schlager
When you look around the XBox Indie Games Channel, there aren't a lot of 3D games around. Most XNA games only feature 2D graphics. I hope to contribute with this tutorial to making 3D graphics a bit less intimidating. And maybe the little prototype we will create throughout the next pages will be the starting point of a great 3D indie game by one of you
We will make a prototype that features the kind of rolling world effect that you can see in games such as Animal Crossing or DeathSpank. We will also create the textures and 3D models that go along with the rolling effect and recreate the combination of 2D art with a 3D world you can see in the game DeathSpank.
Article: I Can Has Platformer? (Part 5)
by Casey Young
Welcome back to the fifth part of my series on how to create a simple platformer game. In this article, we give our hero something to collect.
Article: I Can Has Platformer? (Part 4)
by Casey Young
Welcome back to the fourth part of my series on how to create a simple platformer game. In this article, we give our hero a purpose to live.
Article: Programming your first XNA 4.0 game for PC, Xbox 360 & Windows Phone 7: Pong
by Thomas "Mister Helmut" Altenburger
I’d like to introduce the XNA framework to you with this very simple and straightforward tutorial. We will see what XNA is and how its basic features works to continue with the programming of your first game, a simple Pong clone for Windows. At last, we’ll try to convert it to the Xbox 360 and Windows Phone 7. This tutorial assumes that the readers have a basic C#/.Net understanding. I hope that it will help you to understand the basics of the framework and that it will motivate you to go further in. The article should be suitable to complete beginners in game programming.
About this tutorial: I wrote this tutorial back in the days of XNA 2.0 beta and used it as an introductory course I taught to master degree students. Since then, it evolved to support XNA 4.0 beta with added Window Phone 7 development.
English not being my native language, please forgive and/or report any English oddities.
This tutorial targets XNA 4.0 beta. It will be updated when the final version will be released. It uses some new features of XNA 4.0 so it will not run out-of-the-box on previous XNA version (mainly due to the usage of Viewport.Bounds and changed SpriteBatch.Draw arguments order).
HOWTO: Resolution Independent Rendering in 2D
David Amador shares his code to work with a fixed resolution on Windows without having to manage the placement of your renderables yourself. Sez David:
Independent Resolution Rendering?? What’s this all about?
Basically a way of not caring what you resolution is. Ever had Gui elements misplaced because you changed the resolution? Or getting out of the screen?
If you are doing a game on Xna just for Xbox360 you can basically use a 1280×720 base resolution and the Xbox will scale the game for you making the proper Letterbox.
But what about on Windows? Or if you use a different resolution on the Xbox? You have to manage that yourself.
I’ve made a small example on how to achieve this.
Article: I Can Has Platformer? (Part 2)
by Casey Young
Welcome back to the second part of my series on how to create a simple platformer game. In this article I take you on a little journey in adding our hero to the game, and have him interact with the platforms and blocks that make up the level.