Take that, PC hegemony!
As you recall, OnLive is essentially a game streaming engine for Macs and PCs. All of the heavy lifting happens in the cloud and the company simply streams audio and video to your desktop. Think of it as video-on-demand on crack.
I couldn’t find a way to sign up, but perhaps you’ll be luckier. Incidentally, while I’m intrigued I think this service will be a flop. Just my hunch.