Ford engineers are tweaking the existing sensor package on police cruiser models to remain live when the vehicle is parked.
The rear-camera, front and side impact sensors, and various driving assist sensors are being used to enhance awareness of a stopped cruiser, and will automatically rollup windows, lock doors, and sound an alarm when it detects people approaching from the rear.
According to the clip below, this lessens the risk of sneaking up on an otherwise distracted officer sitting in the car:
Of course, Ford is boldly marketing this to LEO Agencies as a fantastic addition. It seems kind of marginal to me, but it does emphasize the use of backup cameras for more than just driving in reverse.
There is no public pricing for the 'surveillance mode' option, and no word on if it will be adopted into regular production vehicles at some point.