Comment 2 for bug 514336

If it's xserver-xorg-video-ati, then it is probably not the package from Ubuntu: I'm running the xorg-edgers ppa (https://launchpad.net/~xorg-edgers/+archive/ppa):

$ apt-cache policy xserver-xorg-video-ati
xserver-xorg-video-ati:
  Installed: 1:6.12.99+git20100129.5c112645-0ubuntu0sarvatt
  Candidate: 1:6.12.99+git20100129.5c112645-0ubuntu0sarvatt
  Version table:
 *** 1:6.12.99+git20100129.5c112645-0ubuntu0sarvatt 0
        500 http://ppa.launchpad.net lucid/main Packages
        100 /var/lib/dpkg/status
     1:6.12.99+git20100126.e5933fd7-0ubuntu1 0
        500 http://nl.archive.ubuntu.com lucid/main Packages