According to BBC News the new Steam console has been revealed at CES, the Consumer Electronic Show. The console appears to be relatively small and will feature the ability to play Steam games on any TV. It is yet to be known whether or not current Steam accounts will be able to be accessed from the console.
The codename of the console is Piston, as shown in the photo above. The hardware specs have not been released. Given the size of the console it would appear to be a relatively cheap and possibly posses mid range graphics capabilities.