I doubt they expose an API since it's part of the security feature.
So... yes, developers will be able to get their hands on some of this tech, but how much can we do with it?
If room mapping was truly possible, I would imagine they would have done more in their demo with this, e.g. see the Hololens game where robots come flying out of walls, and hide behind your couch. That demo was more substantial than seeing a flat tabletop with a projected 3d game, or a projected 3d robots standing on a flat basketball court.
The AR demos of games use the normal cameras on the back of the device. That stuff will be available to any device 6S and up.