According to AMDZone and ATI's own site, ATI has released 64-bit drivers for XFree86 and Xorg. Here's [2] a link the download page.
Links:
[1] http://www.tuxmachines.org/taxonomy/term/38
[2] http://ati.com/support/drivers/linux/radeon-linux64.html?type=64linux&prodType=graphic&prod=products64LINUXdriver&submit.x=10&submit.y=6&submit=GO%21