Considering Im currently playing the SC2 beta downloaded straight from Blizzard on my Mac, and the Blizzard also releases all their games for OSX theres a high probability that SC2 will run on OSX.
Q: What are the system requirements for StarCraft II?
A: We'll have more details on specific system requirements closer to the release date.
the beta already runs on macs and quite well too. so yes it will upon release too.