Though ATI hasn't officially added new Vsync options in the drivers (it's slated for Catalyst 2.5) the featureset does already exist. To enable it perform the following steps
Run RegEdit
Perform a search for "VsyncSlider". You should find two of them. Their values will be "00 00 00 00". (can be more than 2)
Change both of them to "01 00 00 00".
Close regedit and that should do it.
Open up your Advanced Display Properties. You will see a slider next to Vsync for both OGL and D3D. There are 4 options on the slider for OGL Vsync and 3 for D3D Vsync:
OpenGL: Always Off, Off By Default, On By Default, Always On
D3D: Always Off, Application Preference, Always On