"The National Security Agency isn't the only government entity secretly collecting data from people's cellphones. Local police are increasingly scooping it up, too." "Many people aren't aware that a smartphone is an adept location-tracking device. It's constantly sending signals to nearby cell towers, even when it's not being used. And wireless carriers store data about your device, from where it's been to whom you've called and texted, some of it for years." (thanks Amir)