Mac users only have to wait two more weeks for their own version of Steam. Valve announced that the Mac Steam will launch on May 12th.

If you own the PC version of a game on Steam, you'll be able to play the Mac version for no additional charge. Your saves for both versions will be stored online via Steam Cloud, allowing you to switch off between two platforms while retaining your progress in the game.

Valve will release their future games simultaneously on the Mac, Xbox 360, and PC. The first game that will adhere to this policy is Portal 2.