I bought RA3 for PC a few weeks ago for play in Boot Camp. I didn't even realise they were planning on releasing a Mac version until last week. Anyway, I just bought a copy of RA3 for Mac for my laptop since I don't have Boot Camp on there and I thought I'd try my PC version key in it on my mac pro. Lo and behold, it works! I just thought I'd share my knowledge with others. If you're planning on buying it and so are a few of your friends then you could always just get one mac copy and the rest pc due to the big price difference.