I know it's not going to happen but I would absolutely love C++ support in XNA GSE. Even managed C++ would do. I code games in C++ all day at work and really do prefer it to C#. Don't get me wrong, I do like C# but I prefer the lower level control I get from C++. Particularly in the area of memory management, although that does become a bit of a ball ache when you spend half the day chasing memory leaks as I did today ;)
Still, I wouldn't trade C++ in XNA for the ability to run my games on my 360 so I'm happy enough =o)