Channel9 has posted a great video featuring Kam Vedbrat, lead program manager on the Aero interface being developed for Windows Vista. Well worth the download for those that can spare the bandwidth. Vista will include a re-designed user interface, code-named Aero. The new interface is intended to be cleaner and more aesthetically pleasing than previous Windows, including new transparencies, animations and eye candy.
Download: Vista Interface Demo (460MB)
View: Vista Interface Demo (Streaming)
View: Channel9 Article