Egbert Eich has announced this morning on the RadeonHD mailing list
that rotation support has been added to this open-source ATI R500+ driver. This is a feature requested by many to be able to rotate the screen using RandR
with the xf86-video-radeonhd
driver, which is now possible. It is recommended that if you're using the rotation option that you use EXA
acceleration. In addition, the panning mode currently isn't supported when using the rotation support. This support can currently be found in git master and will appear in the next stable release of the RadeonHD driver.