I have been reading the XNA Express FAQ and it appears that XNA is a copy of the .Net Compact Framework which was originally made for use on PDA and other portable devices that run off of battery. The team has taken that version of the .Net Framework and added a few features to support stuff like 3D Acceleration and other stuff associated with games. As of right now the team only has a C# compiler for the XNA Framework so the coming express edition will only support C#, however they are considering supporting other languages and it is very likely that someone other than Microsoft could write a compiler to support other languages.
This means of course that within a week I will be steeped into learning C# as the only reason I got into computers to begin with was because of video games and I have repeatedly tried and failed to learn to program 3D games using DirectX.
Interestingly is that because XNA is built on the Compact Framework, supporting Mobile phones would be very easy if they started to use 3D chips in them.
If you are a developer and want to get into Beta 1, send me an email and I will tell you where you can signup. I would link here, but there is probably only going to be a limited number of slots for Beta 1 and that shouldn't be filled up with people who will just download the application and then never use it.