Linus Torvalds has criticized some of this Radeon kernel mode-setting work since there are some known bugs at this time (though at least it wasn't called untested crap), but nevertheless he went ahead and pulled in this new code prior to Linux 2.6.31-rc1.
Cheers! There is now Intel and ATI Radeon kernel mode-setting support within the Linux kernel. We now just need to wait for NVIDIA kernel mode-setting to emerge through the Nouveau project, which may come in the Linux 2.6.32 or 2.6.33 series.
Red Hat's David Airlie has went over on his blog the steps needed to take advantage of this new ATI kernel mode-setting support. Fedora already has a version of this ATI kernel mode-setting code within Fedora 11 and there is a snapshot that can be found for Ubuntu ATI KMS testing.