Here is a video of the Xbox Gamerscore Blog guys walking though all the great new features in the Fall update for the Xbox 360.  I really like how they streamlined the Marketplace by having a Game Store and  Video Store.  It was always hard trying to find game videos in the past.  I also like the Inside Xbox that acts as a news section telling you what's new.

The video does a really good job of walking you through the Xbox Live dashboard and shows you how to access these new features and settings. If you've never seen the dashboard and are wondering what a slick console UI looks like you can also check out this video.