Another article taken from Wired...

The police in Oakland (as well as a few other US cities) have started to put in high power microphones all around high crime areas in Oakland to cut down on the rising murder rate. The microphones (shot spotters) will be hidden near each other so that, when gunfire is heard, they can be used to triangulate the source and inform the nearest officer of the incident. So far the mics have been found rather useful; it has allowed the police to respond faster, and in situations where the gunshots might not have been reported.

While I feel that this is a good development, I don't think it fully addresses the issue. While we should spend time finding and bringing to justice those that commit these crimes, we should also strive to make efforts to prevent crime from happening. After the shots have been fired, the damage is done. The ability of the police to catch criminals is still far better than our ability to stop crime.

http://www.wired.com/wired/archi ve/15.04/shotspotter.html