This latest xf86-video-intel 2.20 point release incorporates another couple dozen SNA acceleration architecture fixes plus the PRIME work.
PRIME is the new feature to X.Org Server 1.13, which was releasded this week, and works towards hot-pluggable GPUs and DRI2 offload rendering to other GPUs, which among other uses is a step towards finally having proper Optimus/Hybrid graphics support on Linux. With xorg-server 1.13 out the door, the necessary Intel DDX driver changes were pushed by David Airlie and then Chris Wilson also hooked up the support in an SNA-accelerated world.
For the xf86-video-intel 2.20.7 release that just comes one week after v2.20.6, there's 49 changes by Chris Wilson, five changes from David Airlie, one from Imre Deak, and one from Сковорода Никита Андреевич.
More information and the source download link on this latest driver update can be found on intel-gfx. Coming up in just a few days on Phoronix is a SNA vs. UXA comparison on Intel Ivy Bridge with the 2.20.6 driver + Linux 3.6 + Mesa 9.0-devel when using the GNOME Shell, Unity, KDE, Xfce, and LXDE desktop environments.