This is in connection with the initiated criminal case. We need to find out who took active part in the mass riot and who was there by accident. If you receive a call from a police department, don’t be afraid. It doesn’t mean you will be brought to responsibility. All persons who took part in unauthorized mass riot have already been identified or will be identified in the course of investigation." Yeah, right, don't be afraid...
It is great to have all these location-based apps and technology in your phone, but one should never forget how easily traceable you are, even if you have them turned off, and your location only triangulated by the cell phone towers in proximity. Actually, you don't even need to be in an active call, it is enough that your phone is turned on, and connected to the network.
In the hands of the wrong people, this technology could quickly take a turn for the worse. In the US the authorities have to build a probable cause, and get a warrant to ask for your historical cell tower location data, at least on paper.
source: Charter97 via BoingBoing