I've had the opportunity to fool around with some XNA Studio 2.0 stuff at work recently -- mostly using it as a quick 2D prototyping engine for showing people some system dynamic or another in motion.  I have to say, it is pretty slick.  Combined with the joyousness of C# programming, I've been quite pleasantly surprised how quickly I can turn something around from a discussion of a concept to a running app illustrating it.  Of course some of the cool things it can do (like all the Xbox 360 stuff and the potentially-disruptive distribution model announced at GDC) are not really relevant, but they do add to the package for most people.

When I have a little spare time I plan on making a little weekend project of getting a game up and running at home and on my 360, so I can start to talk to my kids about what programming is.  Heck, maybe I'll make a little educational game out of while I'm at it...