Eye Tracking With The Oculus Rift

Now THAT is amazing, but not out of the question either. Why can’t you do eye tracking with an Oculus Rift? How much more hardware and extra calibration steps would you need to do data collection like this? Seems like a great value add for folks doing Brain and Cognitive Science research with 3D test rigs. Maybe this will open up a market for Oculus Rift as research device.