The GLX_MESA_query_renderer was published almost one year ago to the day and the extension was finally merged in November for supporting the Intel Mesa driver but not other mainline drivers. Emil Velikov has now published a set of 25 patches for supporting GLX_MESA_query_renderer by all classic and Gallium3D drivers. The support for this extension is now on par with the classic i915 and i965 graphics drivers.
The 25 patches yield support for the classic Nouveau, Radeon, and swrast drivers, plus all of the Gallium3D drivers. Those interested in checking out the patches can find them on the Mesa-dev list. This work will hopefully be merged for the Mesa 10.2 version that will be released in about three months.