Decided to note it here so it gets documented: if you're having a fullscreen black screen with Fedora 11 when running glxgears with the r600 Mesa driver, try instead running progs/demos/gears from your Mesa build tree. (assuming you compiled the demos) It's the exact same program, just a newer version. It seems Fedora 11 got shipped with a glxgears that features a bit odd with at least this particular driver.
No announcement yet.
ATI R600/700 OSS 3D Driver Reaches Gears Milestone