Sensor tracks who is driving in your neighbourhood

lock's sensor, which it offers for $50 a year per house, logs the number plates of every car that drives into a street and takes a picture. The sensor could eventually provide facial recognition. Residents of monitored neighbourhoods can opt-out of being tracked - but visitors, or people passing through, cannot. Flock is backed by Y Combinator, a start-up incubator which in the past has funded successes including Dropbox, Reddit and AirBnB.