Since a few days now, the Maverick repositories have an Ati Catalyst 10.10 Pre-release with Xserver 1.9 support 
I've tried it myself on Maverick, works fine.
I thought I'd post about it here in case someone doesn't know about it yet.

I've tried it myself on Maverick, works fine.
I thought I'd post about it here in case someone doesn't know about it yet.