Seems Valve really are trying to do a big push to get Linux graphics drivers up to scratch. Last night Pierre-Loup tweeted about a new hiring and the name might be familiar to some.
Welcome keithp to the team! Our open graphics group is now 5 strong, but still hiring. Shader compiler performance people especially wanted.— Pierre-Loup Griffais (@Plagman2) March 13, 2017
Yep, none other than Keith Packard, a well known name in the Linux community who worked on the X Window System. He previously worked for Intel, then moved to HP and now he's settling in at Valve to continue Linux development. He will still remain at HP while doing this work for Valve too.
This is likely work towards pushing Virtual Reality support and making it better on Linux. Our open source drivers have already come a long way, but now we have some serious people paid to push them even further. Not only that, but game porter Feral Interactive have also been pushing more patches into Mesa. Awesome stuff.