Another round of quick notes about X in unstable while the XSF team is on vacation.
Intel Driver and PAE kernels
If upgrading to xserver-xorg-video-intel broke X or made it very slow, make sure you are not using a PAE/bigmem kernel. The Intel driver now enforces UXA for acceleration. But UXA requires GEM support in the kernel, and GEM is not compatible with PAE before 2.6.31. So if you have PAE in your kernel (CONFIG_HIGHMEM64), i.e. for instance if you are using a -bigmem kernel, your Xorg.0.log will say:
(EE) intel(0): [drm] Failed to detect GEM. Kernel 2.6.28 required. (EE) intel(0): Failed to become DRM master.
Obviously, 2.6.30 should be enough when 2.6.28 is required. But 2.6.30 with PAE is not.
Return of the DRI2 breakage
It looks like the DRI2 breakage in Xserver 18.104.22.1681-3 wasn't enterily fixed in 1.6.2. According to #538637, Xserver 1.6.2 didn't work with KDE4.2 effects when built against Mesa 7.4.4. Fortunately, Mesa 7.5 is in unstable now, and the new Xserver 22.214.171.1241-1 was built against it.