This reminds me of the Dark Knight where Batman had a special sonar which he uses to locate the Joker. The promise he made to Lucius Fox was that he would destroy the technology used to create the sonar. Why? Because it was an invasion of privacy.
It used "every one's" cell phone in Gotham to create a kind of GPS Sonar. And yes that entailed listening in on conversations. The potential for good was present; however, the potential for evil as well. Technology can be a double edged sword and we require better laws; dare I say better enforcement of those laws. Federal and local governments should not be above the law. Thanks for the article.
RE: Police obtain warrant demanding data on all Google users near four crime scenes