ATI has finally managed to produce a driver that executes on the Xorg-server and kernel used by Fedora13. Only drawback is that it produces grey boxes instead of windows and text. In other news, from the SDK’s developer release notes:
The ATI RadeonTM HD 5970 GPU is currently supported in single-GPU mode only. It is recommended users only access the first device on an ATI RadeonTM HD 5970 GPU for GPU compute.
See Pyrit bug #123 for more information and a workaround (that may or may not work for you).