Version 6 of SDL.NET, a high-level binding for the SDL API, has been released. This, combined with the Tao framework, form the corner-stone of MonoXna.
Microsoft created XNA as a comprehensive, high-level API for developing games on the .NET Framework. In their continuing efforts to support .NET on non-Windows platforms like Linux, the Mono project has begun work on a compatible library, MonoXna.
Based on prior discussions, Stuart has chosen SDL.NET and the Tao framework for their cross-platform support.
SDL.NET describes itself as "a set of object-oriented CLS-compliant .NET bindings for the SDL gaming library and provides high-level access to audio, keyboard, mouse, joystick, TrueType fonts, various image formats, sound mixing, MPEG-1 movies, 2D video framebuffer and 3D hardware via OpenGL."