Microsoft was kind enough to already announce the details of the 2007 Fall Dashboard Update that will be rolled out on December 4th.

Update:
Xbox Fall Update available

Among the key new enhancements of the Fall Dashboard Update 2007 are the previously announced Xbox Originals game download service, Family Timer parental control feature, and expanded social networking experiences. Xbox 360 owners can also look forward to enhanced navigation, profile, and video features, and Xbox LIVE Arcade Hits.
This free Xbox 360 Fall Dashboard Update will be digitally distributed over Xbox LIVE to the more than eight million Xbox LIVE members worldwide (Xbox LIVE Silver and Gold) with no disc or hard drive required. If you don't have an Xbox LIVE account, you can easily sign up for the free network by connecting your console to a broadband Internet connection.
More details on Xbox.com.