Forget about Vista/Aero, just look at the visual abuses that are possible in the Ubuntu with AIGLX (coming as standard in Feisty in April 2007). Mostly pointless but tremendous fun.
(Mark Shuttleworth calls providing this kind of facility one of the challenges we need to overcome. He hopes to see usability/productivity enhancements as well as pretty bubbles and lines of fire. I hope so too.)