Is this still a problem with the newer radeon driver in sid (also newer kernel and mesa)? (make sure you upgrade libdrm-radeon1, firmware-linux-nonfree and firmware-linux). If problem persists, could you try getting newer 2.6.33 from experimental. NOTE: When enabling Kernel modesetting, add *radeon* to /etc/modules and put *options radeon modeset=1*in /etc/modprobe.d/radeon-kms.conf (you might need to create the file).
All these things didn't work for my card. If you use NetworkManager, there was a change I made to it that solved all my suspend/hibernation problems. NM has an option called network_sleep. It's disabled by default. I activated it and my laptop was able to correctly suspend and hibernate. What it effectively does, is to disconnect NM before suspending. Report back! Andres
