You can expect a “mandatory” system update sometime today (if not already) when signing in to Xbox Live. It brings a grand total of zero features (at least none that you will see), and is being called a “general system maintenance update”.
Sometime during the early morning hours tomorrow (Pacific Time, Tuesday, October 11th) we are pushing out a mandatory system update. If you are signed into LIVE already, you may be signed out. Once the update has been completed, you’ll be able to sign-in again and back online in a few moments.
This is a general system maintenance update and there are no new features that will show up once your system has been updated.
In related news, new rumours are suggesting the full new Dashboard Update (using modified Silverlight) will be arriving on November 25. Whenever.