It's called "big picture mode," and it's how Valve intends to declare war on consoles. Launching in beta form today, big picture mode is a special interface for Steam that's more appropriate for viewing on a living room television set than the current one you see on your PC. It's Valve's answer to the walled garden approach console makers have taken with their platforms, and could be the first step towards the oft-rumored Steam Box that's talked about every so often.
Don't worry if you're a big fan of Steam just the way it is, the new viewing mode is completely optional and intended for gamers who want take their pastime into the living room, PC in tow. For those that do, big picture mode boasts full controller support, without shunning the keyboard and mouse.
"Steam’s big-picture mode doesn’t require any additional development from you. Just ensure your game works well with a controller, and we’ll take care of the rest," Valve explains on its Big Picture portal. "And don’t worry, keyboard and mouse aren’t going anywhere—users will be able to switch between input devices at any time."
Valve co-founder Gabe Newell has been very outspoken in his disdain for wall garden ecosystems, such as the one he fears Microsoft is building around Windows 8. With projects like big picture mode and recent hirings for hardware developers making the news, it seems increasingly likely Valve is headed towards a Steam Box, which is essentially a PC-console hybrid.
If you want to catch a glimpse of what big picture mode will look like, Kotaku posted a bunch of screenshots of the new interface. Note the larger fonts and icons that are easier to view on a TV, along with an overall look that's somewhat similar to the Xbox 360's dashboard.