Actually there may be a fix to this...
The problem is not something that Redhat can fix. (Unless it backs out the changes to thier kernel.) The same problems occur if you run the 2.5.x kernels.
Look for another thread on Pheobe called "4191 driver and Red Hat Phoebe HOWTO". It has links to the patches that you need to apply and how to get the GL code to work.
I am not happy with the work-arounds. It disables some of the new threading behaviour which a couple of programs I use may or may not depend on.
nVIDIA is going to need to fix a couple things in the driver if they want it to work with the 2.5.x series of kernels.