At ftp://zeniv.uk.linux.org/pub/people/dwmw2/x-radeon there are xorg-x11 packages with a bunch of Radeon fixes backported from CVS HEAD. These should fix a number of problems with X on PPC machines. If you've been having problems, please test these.

You don't really need to update everything; it would suffice just to get ftp://zeniv.uk.linux.org/pub/people/dwmw2/x-radeon/radeon-drv-6.8.2-37.FC4.49.3.radeon.1.ppc.o and save it as /usr/X11R6/lib/modules/drivers/radeon_drv.o