Smokin' Guns is unchanged by Intel HiZ support.
The HiZ support allows for delivering 10% more frames for the Core i5 Sandy Bridge notebook in Urban Terror.
It has taken some time to get HiZ support in place for Intel's Mesa DRI driver and on by default for Sandy Bridge, but this now allows for the performance to go up once again for Intel's open-source Linux graphics driver stack. This is just one of several major performance improvements that the Intel Sandy Bridge Linux driver has seen this year. The HiZ support for Ivy Bridge will hopefully be on by default by the time that the hardware is shipping in 2012.
Now to look forward to OpenGL 3.0 compliance, among other driver improvements still forthcoming...