Last time I spoke to Oculus they said (paraphrasing) that there wasn't a ton of collaboration going on with Valve at the time because most of Valve's VR experts had left to join Oculus. It seems Valve wasn't resting on its laurels though, with a "previously-unannounced SteamVR hardware system" set to debut at the show.
That's all we know at the moment. Valve will be demoing its dev kit during GDC and developers can sign up here.
Some possibilities:
1) SteamVR is a continuation of the outward-facing hardware used in Valve's super-secret-but-not-really VR room up in Washington. Likelihood: Not very.
2) SteamVR looks a lot like the Oculus Rift. Likelihood: Pretty good.
3) SteamVR is actually (like Samsung's GearVR) a surprise partnership with Oculus that nobody sees coming. Likelihood: Hot damn, did you get Vince Russo to write that swerve
Hopefully we'll also be getting our hands on SteamVR next week during GDC and will be back with a hands-on as soon as we're able--plus news on whatever Steam Machines have turned into, and the updated Steam Controller. Phew! It's going to be one busy week.