I have talked about this before. Demoed it all the time. What is it? Well in Vista Ultimate we will continue to update the product with add-ons from time to time. These are called Ultimate Extras and yes they are only available to the Ultimate version of Vista. Well my favorite Extra is Dreamscene. This allows you to take just about any video, make it looping and add it as your wallpaper in Vista Ultimate. Most of the cpu to render it is on the video card, not the core CPU.
Check out the announcement of the release HERE!