Well, there is
this.
I used to use it.. Its pretty and sort of useful, but was still a bit of a gimick and I stopped using it.
As Stu said, Macs have been using hardware accelerated desktops for years, but very under utilised. The only times when you see it are when you minimise something (if you have genie effect turned on), drop a dashboard widget onto the screen (wonderful water rippling), switch user (screen rotates in a nice cube), and iChat where it positions the people chatting at various angles/positions.
---------- Post added at 12:27 ---------- Previous post was at 12:14 ----------
Its nice, but I think like SphereXP the novelty would wear off eventually.
The way the windows wobble when dragged is a bit annoying though.