Few companies have been the target of as much criticism in the Linux community as Nvidia. Linus Torvalds himself last year called Nvidia the "single worst company" Linux developers have ever worked with, giving the company his middle finger in a public talk.
Nvidia is now trying to get on Linux developers' good side. Yesterday, Nvidia's Andy Ritger e-mailed developers of Nouveau, an open source driver for Nvidia cards that is built by reverse engineering Nvidia's proprietary drivers. Ritger wrote that "NVIDIA is releasing public documentation on certain aspects of our GPUs, with the intent to address areas that impact the out-of-the-box usability of NVIDIA GPUs with Nouveau. We intend to provide more documentation over time, and guidance in additional areas as we are able."
It wouldn't surprise me if this is related to the SteamOS announcement.