Valve, the people behind games such as Portal, Team Fortress, and Half-Life have been working on their own alternative game console with SteamOS, a Linux distribution of their own, built on Debian.
I don't play much on Steam, but the Half-Life and Portal series have been entertaining. I've seen people who seem to have every game Steam hosts, which would be quite a few.
I like the idea of SteamOS because the major problem of getting everything working correctly is compatibility. Using a game console, it's fairly easy to have all the software working to a software specification and leave that specification alone. Using Windows, Mac OS X, or Linux, you can't be sure if things match. Even though Mac OS X runs on a smaller set of machines, there are a number of graphics cards and processors and operating system versions that make life (and compatibility) difficult.
If someone would build an interface layer onto an operating system and that would always be reliable, it would solve a lot of compatibility issues. Supposedly, there is an abstraction layer on most operating systems, but to get more speed, system developers allow a way around it.
Can Valve and SteamOS diminish compatibility problems? I hope so. I would buy or build a compatible box in order to just play the games.
Yes, you can build your own, as Valve are giving guidelines on how to do it. Read this Ars Technica article here.
The Debian Linux distribution is probably the most stable for the desktop. It's used as a base for Ubuntu and other distributions, and now, for SteamOS. Why wouldn't they use Ubuntu, which is acknowledged as a good desktop distribution for newcomers? They probably don't want to have to work around all the changes Canonical are making to remove XWindows (thank goodness!) and the slow progress of Unity as a desktop environment.
Apparently, 300 people are beta-testing SteamOS boxes that Valve sent to them. It should be interesting to see how well everything works. When I last looked at the Steam store, they didn't seem to have that many games for Linux, as with Mac OS X. However, if they've used their Source interfaces between the operating system and the games, they should instantly have the same few games that they made Mac OS X compatible.
Will it really affect the latest Xbox or PlayStation boxes? I doubt the change will be noticeable, until they can show momentum for SteamOS. It might be interesting to see Nintendo migrate their games to SteamOS as an alternative, since Wii U isn't really powerful enough to drive sales. (Talk about a missed opportunity! I've got a Wii sitting there, ready to be replaced, and the only thing I'll really get is HDMI compatibility and the ability to buy some US$59.99 games on an underpowered-for-2013 machine.)
The Steam Play Anywhere policy will allow those with Steam games to use them on their Steam box without an extra cost, I'm sure. That's good for everyone because the negative part of moving to a new system is buying new games or new versions of games you already have.
SteamOS sounds like a winner.
Update 2014.04.10: It seems as though this is on the back burner. Since xbox One and PlayStation 4 have made it big, I haven't heard much about a Steam Box, except that the controller has been revised with the removal of the display.
I'm a bit steamed about the Wii U and so are Nintendo apparently because they can't decide what to do. Obviously, the Mario and Luigi brothers haven't driven sales as much as they would have liked. It's difficult to believe that the company would barely outdo last generation consoles and try to continue relying on previous back stories to keep them in the spot light. Had they provided enough power to be considered halfway between the PlayStation 3 and PlayStation 4, they might have been much more successful.
Even if Japanese life has something to do with their choices, they can't expect that the rest of the world will approve.