As Microsoft just announced, one of the first Ultimate Extras (extra features users of Windows Vista Ultimate can download) is a new animated wallpaper feature called "Windows DreamScene".
Windows DreamScene is an animated wallpaper technology that plays high-definition video content as your wallpaper. The key ability of it is that it can do so without using significant amounts of CPU (basically the decoding of the video is the only real CPU use involved). The animation itself is run through the hardware accelerated DWM.
Windows Vista Ultimate users will be able to download additional content through Microsoft as well as through a new site called Dream.WinCustomize.com. The site will include new content, tools, and enhancements to Windows DreamScene.
http://www.wincustomize.com/Articles.aspx?AID=140735
Windows Vista animated wallpapers/backgrounds
Linear Mode
