It's not laser mapping at all. I have some contacts on the dev team, and had a hands-on demo of the unit.
The Lighthouses are actually more of a "ping source", where they broadcast a bright IR sync flash, followed by a rastering modulated laser beam. So it's like a movie clapper board saying "Ok, I'm starting a raster sweep NOW (clap)", and the headset waits for the laser sweep to hit each of the sensor receivers. It detects the different lighthouses by the modulated signal in the laser sweep. Knowing the sweep rate of the lighthouses, and timing the difference between the receptors, it calculates the X/Y/Z/ of each sensor. Wicked cool.
I was surprised by the effort they had to go through to get very smooth running motors (thanks HD motor manufacturer technology!) to reduce the jitter.