It seems that Microsoft is on a banning spree. It's being reported that Microsoft has banned up to one million players from Xbox Live, because they have been playing on modded Xbox 360 consoles.
"All consumers should know that piracy is illegal and that modifying their Xbox 360 console to play pirated discs violates the Xbox Live terms of use, will void their warranty, and result in a ban from Xbox Live."
"We can assure you that if an Xbox Live member follows the Xbox Live terms of use, purchased a retail copy of 'Modern Warfare 2' and played the game on an unmodified Xbox 360, no action will be taken.”
Call of Duty MW2 was pirated to hell and back a couple of weeks ago by Xbox 360 users. Because of that, it's most likely that Activision has been pressuring Microsoft to ban all modified Xbox 360 consoles in time for the games release.
Those who aren't banned, there should be a Xbox 360 Dashboard update coming on 17th of November that contains Facebook, Twitter, Last.fm and Zune video.