Our bud Regeneration from NGOHQ posted a new Catalyst beta driver today.
It's the new 5.11b version and the package includes the following:
All ATI Radeon graphics cards from 9500 and upwards towards the new x1800 series are supported.
EDIT: this is 5.11b not a 5.12 beta (according to ATI).
Use it at your own risk!