There’s a new Xbox 360 Update (September 23, 2009). There are no new features in this update however, this is in preparation for some additional system enhancements like integration of Facebook, Twitter, Last.fm. Users are required to sign out of Live to download the update.
The update was available starting around 2:00AM ET Sept 23, 2009. There were some initial complaints about not being able to reconnect to Live but it was already resolved.