SteamOS will be made available when the prototype hardware ships. It will be downloadable by individual users and commercial OEMs. (But unless you're an intrepid Linux hacker already, we're going to recommend that you wait until later in 2014 to try it out.) We'll post info soon about that. Oh, and stay tuned for the in-home streaming beta to begin soon, too!
The first moment of truth for Valve.