Origin, Electronic Art's digital distribution platform, is available for Macs as of today via an open alpha testing period From MacRumors:

Origin for Mac was initially announced in August of last year, when EA noted that the Mac version of its upcoming SimCity game was expected to launch alongside the PC version. SimCity will no longer be released simultaneously on the Mac and the PC, but EA will presumably release the final version of Origin for Mac before the game comes out in March. Like Steam, EA's Origin allows users to purchase and download games, chat with friends, and continue saved games from any Origin-enabled computer.

 EA Announces Origin for Mac Alpha Testing