At the Game Developer’s Conference yesterday, Valve announced that its Steam PC gaming platform will soon get a “big picture” mode, enabling controller support and other navigation options designed for playing on a TV. The new mode is the first step toward bringing the Steam game store onto new devices.

“Our partners and customers have asked us to make Steam available in more places. With the introduction of Steam on the Mac, and soon in Portal 2 on the PS3™, we’ve done just that,” said Doug Lombardi, VP of marketing for Valve. “With big picture mode, gaming opportunities for Steam partners and customers become possible via PCs and Macs on any TV or computer display in the house.”

In January, Valve also announced that the PlayStation 3 version of Portal 2 will connect to Steam as well, allowing PC, Mac, and PS3 players to challenge one another.

Steam is a cloud-based PC game platform and store. Like iTunes, to use it you must download the Steam program on your PC. Once installed, you can purchase video games and download them onto your PC. Game saves are stored in the cloud, as are copies of the games themselves, which are always available for re-download should you want to reinstall them on a new PC. Valve, publisher of the Half-Life and Counter-Strike series, has had immense success (30 million accounts) with Steam on PCs, but has yet to bring the platform to new devices in a meaningful way.

Is “big picture” mode a taste of things to come? Would Sony, Microsoft, or Nintendo allow a Steam store app on their consoles?