The Starcraft 2 beta has been open for about a month on PC, but may soon be coming to the MAC!
In a recent Blizzard Developer Chat Zarhym said they are, in fact, working on a Mac version to be released in April!
Q. Mac beta please! Any information?
A. We are currently working on a Mac version of the beta and hope to release it sometime in April. Hang in there!! :)
Be sure and checkout SC2Mapster.com to stay updated with all the latest news for Starcraft 2!