From what I've learned in the released videos of Steam Dev Days, and Oculus Rift's interviews on Tested, I'm surprised to see Sony's prototype is using a variation of PlayStation move with only four LEDs (according to the mockup render). While the PlayStation Move can have a bit of delay when playing wand-based games, head tracking has a VERY SMALL tolerance for delay before users get motion sickness. So far, the solution Oculus had was a camera tracking the Rift that is PLASTERED with white dots all over the damn thing (CastAR's solution was a camera system on the glasses that tracks reflected light onto itself). This not only allows accurate rotational tracking, but also position tracking. Only problem being you were forced to sit and not stand.

I'm going to assume Sony also has positional tracking even though they didn't explicitly say so (head orientation and movement could simply mean rotational only, at this time). If so, I wonder what Sony did to reduce lag in their solution? I just don't see enough reference points on the VR headset for the camera to track in all possible head movement combinations. And anytime the VR headset loses tracking, the movement stutters, and when that happens your brain with expectations on what should happen, will not see what should happen, which creates confusion. That confusion will make you nauseous, thus motion sickness. Still, three years of development and all I got are speculations on a mock-up picture, so perhaps my worries are premature.

I am curious to see how that thing fits on people with glasses though.