Major Nelson announced on his blog that a new Xbox Live update is coming to all Xbox Live users today.  The update has been staggered, so it will not hit everyone at the same time.  A few countries and/or time zones will get the update at any one time.

Alas, there are no new goodies in this update, but it was implemented to address some recent communication issues that have been happening to some users in certain online games.  Not very exciting.  I was hoping it was a cover for the patch actually making The Pitt DLC playable.