I viewed the lane alert camera tear-down, with the MobileEye chip.
I had the opportunity to hear a lecture from MobileEye CTO, and they are doing a lot of real time video processing. One of the amazing things they do is that they can classify object, and calculate these objects distance with only one camera, not two !!
Don't ask me (I have no idea) or them (they won't tell you) how they do it.
Johanan