A new framework built on top of XNA has arrived: 'Game Maker Studio .NET'.
You can check the author's blog, visit the forums, view some screenshots, browse the Wiki and of course, download the latest version of the framework.
From GMS .NET's site: "Through working with RMXP building scripts and seeing the limits of the engine I left RMXP to build a new editor and engine. I had an idea for a good system for building 2d games or at least 2d RPG games. So I asked around and found people willing to help with the project. But sadly they have all left one way or another. That forced me to rethink the development since I was depending on some of these people for different parts of development. I changed the direction of the project and went away from ruby as my programming language and away from developing an in-house graphics package and maybe from a graphics package all together. When this process was working itself out I found the XNA framework the brain child from MS for a simple and easy way to develop games. Well in truth it does make life a lot simpler in terms of lower level control but lacks a great deal of higher level control and content control. The idea struck. Build an editor to layer over the XNA framework. But the hard part was how to do it away that lets the user and community develop the product’s future. So I designed a shell in which new elements can be added to a project and thus changing the editor the engines and the game. Thus through community development this product can be changed to model the needs of the community. It was at this point that Game Maker Studio .Net was born and The Game Wizard died."