Saw it on slashdot last night, looks like lots of games are already ported...

From what I can tell from the installer, it is really meant for Ubuntu 12.x 32bit systems, but I've read reports of folks using it on 64bit systems...

http://store.steampowered.com/browse/linux/

Personally, if you can afford it, I think "we" (Linux users) should buy what we can, show that there is a market for our platform. I did it with Loki games and their original ports, and I'll be buying a few games this weekend on steam - assuming I can get it to install on a Mint 64bit system.