The second edition of XNA Game Studio has been released for Visual Studio 2005. We covered the new features in November.
XNA Game Studio is Microsoft's toolkit for developing games on Windows and the XBox 360 using C#. Basic game development is free for Windows developers, but XBox users need to join Microsoft's XNA Creators Club. The Creators Club also gives developers access to XBox Live services.
XNA currently does not support Visual Studio 2008 or any .NET language except C#. It will work on any version of Visual Studio 2005, but VS Service Pack 1 is required. Also, anyone using a dual-core AMD processor needs to install the AMD Dual-Core Optimizer.
Part of XNA, specifically the Cross-Platform Audio Creation Tool, also requires .NET 1.1. More information can be found in the readme file.