The xf86-video-intel 2.17.0 driver incorporates a lot of bug-fixes, particularly for Sandy Bridge and forthcoming Ivy Bridge graphics processors. Sandy Bridge New Acceleration (SNA) has also matured a great deal thanks to Chris Wilson.
Among the notable bug-fixes since the xf86-video-intel 2.16 release several months ago is the video clobbering composite batch state, incorrect reuse of surface bindings workarounds for SNB/IVB blitter hangs, fixed Sandy Bridge pipe control, using the correct maximum PS thread count for Ivy Bridge, and protecting against failed pixmap allocations with X-Video.
The xf86-video-intel 2.17.0 release announcement can be read on the mailing list.
Moments after the xf86-video-intel 2.17 driver was tagged and released, the initial Glamor acceleration support was merged to master, which will make for an interesting xf86-video-intel 2.18 release in 2012. Like SNA, Glamor is currently disabled by default and must be configured at build-time.