Valve has done some foundational research and they've already released VR support in Steam, but don't plan to sell hardware. Oculus is designing hardware and working with Valve along with many other game devs. They will likely release an awesome consumer product in about a year.

Oculus + Steam OS will be the best VR platform for the foreseeable future. Everyone else is at least a year behind; probably much longer than that.

Here's a dark horse which might become interesting soon: http://highfidelity.io/