I've heard Steam will support Linux, but I can't wait.
So I want to know if it is possible to play Dota 2 using wine or something. Has anyone tried? I'm on Ubuntu 12.04, and I have never used Wine, so I'm not sure how it works.
Yes, actually. Wine will run Steam and DotA 2 (along with other source games, including TF2) fine. There are some particle rendering and lighting issues though. Also, performance varies by desktop environment. XFCE and LXDE have the best track record, where Unity and KDE have the worse. There is also a pulseaudio bug that crashes your game when it tries to get direct access to sound hardware, there is a fix. More at the wine appdb entry.