Safari and Chrome do support hardware acceleration for 3D CSS transforms.

Runs great on a run of the mill >2 year old PC w/ Windows 7 and Chrome 12. I'm sure YMMV depending upon quite a few factors, but I was actually surprised how nice and smooth it was for me.

If you are using Chrome, go to chrome://gpu-internals/ and make sure that hardware accelerated compositing is enabled.

GPU support is still disabled on many configurations, you can enforce it by starting Chrome with '--ignore-gpu-blacklist' option.

its actually really smooth for me.