The latest update of Mac OS X includes fixes for ATI videocards (‘Includes fixes for possible graphics distortion issues with certain ATI graphics cards.’).
Blender was still usable (no crashes, but sometimes rather slow) on my Macbook Pro after the dreaded 10.5.5 update, but my first tests with 10.5.6 indicate a big performance increase.
While it’s not without problems, it may be worth while to try this out of you can’t use Blender on your Mac. Please let us know if this solved the OpenGL issues for you!
