I purchased a copy of Starcraft II the day it was released, and have been playing the game ever since on my HP desktop PC. I decided to try installing the Mac version on my Hackintosh build, and sure enough, I was able to download the installer from Blizzard's website.
Since I already have an account, I was able to install the game and instead of activating it, skipped this step and just let the installation finish. When I ran the game, all I had to do was put in my user name and password, and there was the familiar game interface before my eyes. I am glad Blizzard decided on this single-account-on-multiple-machines feature, as it allows me to install the game on all my computers be it PC or Mac, and only have to remember my user name and password.
I was able play a couple of skirmishes with good graphics acceleration and framerates, without any lag whatsoever.