A passive radar system that uses cellphone towers to track every vehicle on the road! So the this Business Week article screams - at least to my privacy liking mind. (Link via Gizmodo)

Here is an actual company’s site on Celldar. From looking at the diagrams, one of it being used to watch traffic, I see there is nothing magic here. Someone finally is making use of all that “free energy” that is constantly being emitted from known fixed points.