Intel remains backing their classic i915 and i965 Mesa DRI drivers rather than jumping on the bandwagon. The i915g Gallium3D driver has managed some level of adoption due to the backing of Google and other select organizations working on this independent open-source Linux 3D driver, but the i965g driver never really received much love outside of Tungsten Graphics (now VMware) and select others for a short period of time. Fortunately, there's now a brand new i965g driver.
This new i965g driver isn't based upon the earlier Intel Gallium3D driver and it also still doesn't have the backing of Intel's Mesa developers. This new i965g driver has been largely spearheaded by Chia-I Wu, the open-source developer that previously worked on Android Mesa support, the Vega state tracker, and various other contributions over the years.
After Chia-I Wu started work on this new driver, it became sponsored by LunarG. While called i965g, this driver is currently only targeting the Intel Sandy Bridge "Gen6" series and newer (Ivy Bridge "Gen7", etc) but not the earlier generations of Core/HD graphics going back to i965.
Aside from not being based upon the former i965g driver, it's also not based upon the i965 classic DRI driver although it does share some common design traits. For right now the i965g driver is also employing a rudimentary compiler for translating TGSI tokens to GEN instructions for the Intel hardware and unfortunately this isn't yet well optimized for better performance. "The driver is written from scratch. However, it follows classic i965 driver for many of the design decisions. It comes with its own toy compiler to translate TGSI tokens to GEN instructions. The compiler still lacks several functions (register spilling and most TGSI indirections), but more importantly, almost no optimization is performed. It thus generates much worse code comparing to that generated by classic i965."
In terms of how far along this driver is, Chia-I describes it as, "While it is still new, it does work for many of mesa-demos. Right now it passes 6884 of 7547 piglit quick-driver.tests. I also tried it with gnome-shell, OpenArena, and Nexuiz, and they all seem to work."
This new i965g driver is not yet merged into the mainline Mesa repository but Chia-I Wu is requesting permission to do so. For now this Mesa repository is being hosted on GitHub. Without the backing of Intel, the i965g driver is unlikely to replace the i965 classic DRI driver anytime soon unless the Intel developers decide to change course and become interested in Gallium3D.
Benchmarks of the new i965 Gallium3D driver will be conducted on Phoronix in the near future. For more details on this new open-source Intel graphics driver, see the mailing list announcement.