It's all coming very soon, I would just wait a bit longer... well, I *do* wait, because I've got a R580 and Debian/sid, tooWaiting for stable release of xserver and mesa-libs is painful. Because nobody know when it will be released.
I guess you're missing a new Xserver. Xserver 1.5 RC2 is avaible in experimental, it is a bit over a month old, but honestly, I would just stick to Sid and wait (and maybe use fglrx for the time being if you need 3D).
Btw.: Are you using Radeon 6.9.0? If you're using RadeonHD, the latest release 1.2.1 does not support DRI etc. yet.