Just an FYI, I just installed the latest kde updates and AA is not working for me. I've seen a few posts on the subject, but I thought I'd mention that the latest update didn't solve the problem.
I had it working fine under the sid/unstable kde packages, but when I grabbed the alpha bits things broke. I do show that libqt.so is linked to Xft and Xrender, and my xdpyinfo does report RENDER. I'm using the latest X debs from Branden's repository. Hope this info helps, -Brad
