It turns out XGI actually works on their Linux driver code from Windows systems, as was said by Jong Lin. This actually begs the question whether XGI Technology actually tests out the xf86-video-xgi Linux driver or to what extent. However, as sad as it may be, soon enough they could actually have more notable code contributions than what VIA is doing with their open-source work and outpace their "efforts" from years past.
For what it's worth, XGI Technology primarily advertises their open-source graphics hardware support now and not their binary Linux drivers. In fact, it takes some navigating to find their Linux blobs, but the Volari Linux driver was last updated in January of 2006... This was their update that added Linux 2.6 kernel compatibility and 3D support. Don't even think about running this binary driver with a recent kernel or X Server. Though you can find their open-source drivers for the V3XE, XP10, Z7, and Z9 on this page. No open-source 3D stack has yet to be published. XGI Technology has also abandoned their NDA-ladened developer area that we had access to and was more interesting.