Valve is holding a developer event in January, and the session list reveals some interesting tidbits about the company's plans for virtual reality. Programming wizard Michael Abrash is holding a session on "What VR could, should, and almost certainly will be within two years." He'll show a prototype based on the sort of VR hardware that's expected to be available to consumers in a couple of years. It's unclear if this means Valve intends to produce a headset of its own, though.
The Oculus Rift seems to the the leading candidate for consumer headsets, but the final version isn't ready yet. Its inventor, Palmer Luckey, is leading a session titled "Porting games to Virtual Reality." Luckey has said in the past that the Oculus folks are good friends with Valve, so I wouldn't expect the two firms to offer competing headsets. There's probably plenty of potential for collaboration, especially given Valve's desire to enable hardware makers as part of its Steam Machines initiative.
The Steam custodian is also prepping its content distribution service for virtual reality. Valve is working on a VR-specific Steam overlay, and it has plans to tweak the store and Steamworks with VR in mind. The company has already adapted Steam nicely to the living room with its Big Picture UI. A virtual Steam store could be interesting.
Of course, there are plenty of developer sessions that have nothing to do with VR. Valve will discuss Linux development, in-game economies, and user-generated content, among other topics. Steam Machines and the Steam Controller will get some time in the spotlight, too. Unfortunately, we may not hear much about what's said. Steam Dev Days is an "off the record event," according to the official FAQ. The press doesn't appear to be invited.