Anyway, if you don't want to wait for the kernel packages, the X.org wiki has cool instructions on building the latest DRM from source, and they just worked for me like a charm! For some extra confidence, I also did a "depmod -a" and "update-initramfs -u" after copying the modules in their places.
If everything goes well, here's what you'll get in your Xorg.0.log:
(==) RADEON(0): Using EXA acceleration architecture
(II) RADEON(0): Acceleration enabled
And of course, the difference is easily noticeable. Especially if you like moving and switching windows :) The video support is also outstanding. Even high resolution clips (like Big Buck Bunny or the Ruby videos) play VERY smoothly and are quickly switched into and out of fullscreen. Really cool! And they say, EXA acceleration should work with radeonhd as well by now, but I haven't tried this myself yet.