At present, Mac OS X does not accelerate the video on ATI Rage Pro chipsets. However, it appears the 10.1 CD contains at least a preliminary solution to the problem. On the MacFixIt Tips and Hints board, the RagePro Fix thread contains "Sysadmin's" hack for enabling ATI Rage Pro support. Basically, the hack involves taking some drivers that are on the 10.1 update CD and placing them on your boot partition.
If you have a Rage Pro machine (I don't, otherwise I'd try this for sure!) and would like to try this out, respond here with a comment as to the success or failure of the experiment. Obviously, you should have a good backup going in, because I would guess that Apple did NOT enable these drivers for a reason! However, the fact that they are even there is good news for Rage Pro owners -- it appears support is coming, at some point.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20011025184729669