Brian Burke of NVIDIA's PR team posted a blog post interview with Mike Sartain, the leader of the Linux group at Valve Software and someone who I've known from the early days of the project. The NVIDIA blog post doesn't add too much that Phoronix readers don't already know, but that NVIDIA GPUs were called into play with NVIDIA and Valve have worked together for more than one decade and NVIDIA has shown much interest in SteamOS and Steam Machines. NVIDIA's also been quick to respond with driver support, porting NVIDIA's content library, etc.
Sartain also said, "Everyone at Valve and NVIDIA believe the SteamOS open ecosystem is a very important move for gaming. It has the potential to redefine the living room experience...NVIDIA has done a ton of work to optimize its GTX GPU series on Linux...The GeForce GTX series delivers the graphics performance, acoustic characteristics, and power efficiency we wanted for the first impression of the SteamOS living room game experience."
Read more in the NVIDIA blog post.