Steam Box is a concept console from Valve and, according to Gabe Newell, it will be Linux-based, although it's not going be limited only to the open source solution.
A lot of rumors have circulated before and during CES 2013 about a possible Steam console, including one about an interesting mini PC called Xi3.
As it turns out, there will be a flurry of third-party Steam Boxes, from various developers and even Valve will produce one, although it's not going to be available in 2013.
Gabe Newell, Valve's boss, was interviewed by The Verge at CES 2013 and he talked about the Linux-based console that will eventually arrive.
“We’ll come out with our own and we’ll sell it to consumers by ourselves. That’ll be a Linux box, [and] if you want to install Windows you can. We’re not going to make it hard. This is not some locked box by any stretch of the imagination.
“We also think that a controller that has higher precision and lower latency is another interesting thing to have,” stated Gabe Newell in the interview.
He also pointed out the Steam Box will probably be available in three flavors: Good, Better, Best. One will be a low-cost solution and the others will have a dedicated CPU and GPU, which in turn will be tightly controlled in order to insure an even quality standard.
Moreover, the Steam Box will also act as a server and Newell pointed out that future GPUs will be able stream content over multiple monitors.
An engineer also went on record last week and confirmed the information that Valve was working on a console, but the 2013 deadline he hinted at was misinterpreted.
As it stands right now, it's impossible to say when the Steam Box will be available to the public, but the most likely date is sometime by the end of 2014.