SteamOS Beta is the first public release of our Linux-based operating system. The base system draws from Debian 7, code named Debian Wheezy. Our work builds on top of the solid Debian core and optimizes it for a living room experience. Most of all, it is an open Linux platform that leaves you in full control. You can take charge of your system and install new software or content that you want.
No surprises there, but still good to see.
Additionally, Steam Machines have shipped to beta testers; here’s an requisite unboxing video: