I've been playing around with XNA a little bit in my free time. It's pretty darn easy to build a simple game with. You can debug it from your Windows machine while running on your Xbox 360, all good stuff!
Be sure to check out the XNA content on Channel 9 too.
P.S. Don't mind the typo on Learn XNA. "not" should be "now". 😉
Major Nelson talks about it here: http://www.majornelson.com/archive/2006/11/22/video-marketplace-now-live.aspx
I turned on my 360 today to find all kinds of cool new ways for me to spend some points. 😉 It's pretty fabulous. They've got shows for bunches of major networks, movies (old & new), etc.
I'm downloading THX 1138 (still haven't seen it and I feel ashamed as a George Lucas fan). I love that they have entire seasons of shows. What I'm disappointed in though is the fact that the only TV shows they have in HD are all the CBS shows. So if you wanted to watch the latest Studio 60 episode in HD you're out of luck. Hopefully this will change in the future. Overall I'm loving this though! I'm going to need a bigger hard drive soon. 😉