Valve spokesperson says Steam Box will use Linux; is due for full reveal in 2013
According to a report on German tech site Golem.de, Valve will unveil Steam Box some time in 2013. Speaking at the EHSM 2012 conference in Berlin last month, Valve electronics engineer Ben Krasnow reportedly confirmed that the Steam Box will run on Linux as well - no surprise to anyone who remembers Gabe Newell's anti-Windows tirade last year.
According to the report it's expected that Steam Box will be detailed at either GDC 2013 in late March, or E3 2013 in June. These details line up with Newell's own admissions last year that Valve are working on more living room-friendly hardware.