On Sunday there was a commit by Marek Olšák that was entitled r300g: kill the X.Org state tracker target. Marek's reasoning for this comes down to, "This won't ever be made default and we don't need it anyway. We should also consider doing this for other drivers."
For R300 through R500 (Radeon X1000) class hardware as supported by this open-source Gallium3D driver already has the well oiled and tuned xf86-video-ati DDX driver that has proper 2D/EXA acceleration plus as of last year can optionally rely upon the GLAMOR acceleration architecture. The X.Org state tracker has been available for use with R300g, but hasn't seen any widespread or serious adoption.
Back in August of 2011 I wrote about my experiences with using the Xorg state tracker on R300g -- it wasn't too good. R600g also supports this state tracker as does Nouveau and the AMD "RadeonSI" driver, but we may see the support dropped per Marek's commit message.
The only vendor really concerned about doing 2D in Gallium3D has been VMware. With VMware's virtual graphics stack they were using the X.Org state tracker but then eventually the acceleration paths turned into the XA state tracker that they are still using within their "vmwgfx" virtual graphics driver stack.