Strange, the Valve stuff isn't on the GDC schedule anymore and nothing was revealed. There are still two Valve events listed, but they don't sound very interesting:
2015/03/04 05:00 PM - 06:00 PM | Alex Vlachos (Valve Graphics), Advanced VR Rendering
2015/03/05 10:00 AM - 11:00 AM | Valve, The Future of High Performance Graphics
They won't let any reviewers talk about the Vive (their personal impressions) until some point Wednesday. I don't see any more HTC/Valve stuff on the schedule than the stuff above. Lame.