Steam has been a service exclusively for PC users since we launched it in 2004. For the first time we and our partners are bringing it to another platform. It's been a ton of work, but the Mac is great for the same reason the PC is great - they are both open systems that let gamers and game developers be as close as possible.
So check it out. If you have a Mac and are new to Steam, welcome! If you've been with us since the beginning, borrow a Mac and log into your Steam account and jump into a game. And for everybody, Portal is free from today until the 24th.