For the benefit of those living under a rock, Steam was released for Mac this month.
This
is great video discussion with Gabe Newell (head of Valve), and Jason Mitchell (Software Engineer at Valve who focussed on the efforts to get Steam on Mac).
I think it's great to hear a major games developer discuss some hard data points to back up the long suspected Apple Mac graphics performance discount. Valve have done good work getting their code to run well on Mac, and they're pushing hard to help Apple improve the (lock stop) graphics drivers and OpenGL Frameworks that are released with each release of OS X.
I dare say the experience of more gamers using a stable, well developed code base like Steam on Apple will help expose the lingering bugs in the APIs and SDKs released for OpenGL development on Mac. As the developer tooling gets better over the next year, big improvements should be seen.
Which only bodes well for FS2_Open and other OpenGL apps on OS X!