ATI drivers are horrible on the Mac OS X platform too, even though Apple controls all their drivers on the platform. Even though Intel's GPUs are slow their drivers are very stable and work most of the time.
AFAIK there's no route for an IHV to get an updated driver to a user without going through Apple, put it that way.
GPU driver: http://www.nvidia.com/download/driverResults.aspx/73628/en-u... Additional CUDA driver: http://www.nvidia.com/object/macosx-cuda-6.0.37-driver.html