The ILO Gallium3D driver has principally been the work of LunarG for experimenting with Gallium3D and having a lightweight hardware driver for conducting their tests. The ILO driver currently supports from Sandy Bridge through Haswell generations of Intel HD Graphics hardware. The driver doesn't have the performance nor feature-set of Intel's official classic Mesa DRI driver and is not officially supported by Intel Corp. There's been ILO Gallium3D benchmarks on a few occasions for those interested and the driver is part of mainline Mesa.
There's been more ILO driver improvements merged this weekend by Chia-I Wu of LunarG, which includes work for enabling fast depth clears.