At the Microsoft E3 press conference Microsoft announced the integration of Facebook and Twitter to XBL sometime this Fall. You will be able to post screenshots and text from in game with the new Facebook connect feature starting with the upcoming Tiger Woods PGA Tour 2010 game. Twitter will allow you to post tweets right from your 360.
Not bad add-on features for XBL. I know these features will be used by a lot of people out there. I am a user of Twiiter and this new and upcoming function will be used by me for sure.