Sering this, I think the same thing I did when I first saw quadrotors on Youtube: So, when do things like this replace cameras and helicopters as high tech policing tools?

Just place charging stations around the city that they can land in (in this car, or affix to in the case of quadrotors,) and you've got an extra pair of eyes on the street able to cover far more ground than a patrolman. (Though, you'd stol need someone to pilot them. For now.)