Felicia Day (of The Guild) just demonstrated a new Xbox Live version of Facebook. Facebook on Live uses NXE-style navigation, allows you to view both of your Xbox friends and your Facebook friends in the same interface. Most interesting: the ability to post text and even screens from in-game. So now, not only will you get to voice chat with annoying jerks on Live, you can see what they're playing and read about their chemistry exams or whatever.
Also: Twitter is coming to Xbox Live! We'd say more about it, but that isn't in the spirit of Twitter.