First up, for Steam on Linux/SteamOS that are using NVIDIA graphics cards with the proprietary driver, NVENC hardware accelerated encoding is now supported using the NVENC API. NVENC is to encoding as VDPAU is to video decoding on the NVIDIA Linux stack. While NVENC has been available for a year and a half, it's great to see the Steam client now supporting it for a better in-home streaming experience.
This Steam client update also enables drag scrolling within Steam's Big Picture mode, SteamVR updates, and a number of in-home streaming improvements.
Some of the Steam controller work in this update includes better support from the desktop interface, improved speed of downloading/publishing configurations, improved reliability when changing settings in-game, auto power-off options, a variety of fixes, and other improvements.
More details on this new Steam client beta can be found via SteamCommunity.com.