The Steam Machine is the highly anticipated console/PC system from the gaming masterminds at Valve, the software house responsibly for a number of hugely popular titles, perhaps most notably the Half-Life franchise. It runs SteamOS, an open-source Linux-based operating system, and will support loads of games in the Steam catalog. (And still more are, obviously, on the way.)
Given the open source nature of the OS and the ease with which users can get inside the box and re-jigger its components to their hearts' content, the Steam Machine looks to be a hacker's dream come true.