The Mac version was originally set for a February release, but was delayed to June 11th and then again delayed until August. The PC version of Sim City was released back in March.
SimCity's PC launch was more than a little rocky, largely because the game can only be played online. EA requires that the game be connected to its servers at all times to facilitate 'region play' where the cities of multiple players are connected to share utilities and citizenry.
At launch, SimCity's servers were overwhelmed with traffic and the gameplay experience was extremely poor. Today, EA seems to have ironed out most of the bugs and users are playing the game as intended.
Currently, the PC version is available via the EA's Origin store for $40, or as a digital deluxe edition with extra buildings and add-ons for $60.