Fedora 12 provides "out of the box" support for kernel mode-setting with ATI R600/700 series graphics hardware, but it does not provide 3D acceleration by default. However, Red Hat's X developers have made it very easy to enable this 3D support for the ATI Radeon HD 2000, 3000, and 4000 series hardware by just installing a special Mesa package from yum.
To enable the open-source R600/700 3D support under Fedora 12 one must simply run
yum install mesa-dri-drivers-experimental
and then reboot their system