Minneapolis -- the city I live in -- has an acoustic system that automatically detects and locates gunshots. It's been in place for a year and a half.

The main system being considered by Minneapolis is called SpotShotter. It could cost up to $350,000, and some community groups are hoping to pitch in.

That seems like a bargain to me.
Recently, I was asked about this system on Winnipeg radio. Actually, I kind of like it. I like it because it's finely tuned to one particular problem: detecting gunfire. It doesn't record everything. It doesn't invade privacy. If there's no gunfire, it's silent. But if there is a gunshot, it figures out the location of the noise and automatically tells police.
From a privacy and liberties perspective, it's a good system. Now all that has to be demonstrated is that it's cost effective.
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