In March 2013 Oculus started accepting pre-orders for the second-gen development kit (the DK2) - which adopts a new low-persistence OLED. A couple of days ago, Oculus said they are starting to ship the first batch $350 kits. In the first stage they will ship 10,000 units ouf of the 45,000 pre-orders they got (the rest will have to wait a bit, probably till August).
Oculus changed their design from an LCD to an OLED because they really want a low persistence display. They say that "it’s incredible the difference low persistence makes... It’s mind-blowing". The OLED display runs at a high refresh rate - it switches in well under a millisecond. This is the fastest OLED on the market, supplied by Samsung.
Samsung is in fact developing their own virtual headset in collaboration with Oculus. In this collaboration Oculus provides the software while Samsung provides the hardware. As part of the collaboration, Samsung gives Oculus early-access to its next-gen high-resolution (larger than Full-HD) OLED displays.