Honestly, one of the biggest uses for a new graphics card under OS X is having additional video memory.
How Much Video Memory Do You Need in Mac OS X? I've been considering doing more things like this in the future, where you get pieces of a review as I finish them before the full thing is done. I just finished writing a section about GPU memory usage under OS X (since the 285 has a hefty 1GB frame buffer) and thought I’d publish it as a standalone before the review is done.
As I mentioned in an earlier post, I’m working on a review of EVGA’s GeForce GTX 285 Mac Edition.