The 3D is much much improved. However leaving parsec (www.parsec.org) running the demo on my G450 hangs the X server solid within 30 minutes or so. No kernel messages, but X gets stuck and you have to login remotely and reboot it. Athlon 550 256Mb RAM Matrox G450 (cheap version with non DDR RAM) ES1371 audio data coming off a AMI MegaRAID - and that seems fine still when X seizes I'm hopeful you can reproduce this one and may have ideas on how to debug it, if not we can set up remote access from inside the RH network for testing and poking around when it hangs.
This is fixed by a combination of XFree 4.2 and the DRI fix for matrox posted to the dri-list