If you've already purchased SimCity for PC you can download it for free via Origin on Mac. That's a solid humanitarian move EA.
"SimCity is coming to Mac on June 11 and one purchase will give you both the Mac and PC versions. You only need to buy SimCity once to play together across the same servers, regardless of which version you're playing," said Lucy Bradshaw, Senior Vice President and General Manager of EA's Maxis Label. "We didn't want to make any compromises when it came to the Mac so we created a native version that is optimized for the hardware and OSX."
I still have faith Maxis, I do.