The Post has an article talking about gunshot sensors that have been installed in the District to help combat the most violent of crimes. It’s a really cool idea - one that I had heard about in Chicago before Hedda and I moved here.
The idea is simple: With a few sensitive microphones and a little bit of digital signal processing, you can triangulate the location of gunshots to within - it used to be a block, but the article says things have improved - a few feet. Since even owning a handgun is illegal in The District, and all rifles and shotguns must be unloaded and have trigger locks, sending police to the triangulated location of a gunshot is a good bet.
These things are a far sight better than the cameras MPD has been hanging all over the city. I really dislike the idea of the police watching over my shoulder constantly, and quantifying the effectiveness of cameras has proven difficult. 
Still, here in DC, they have gone up with relatively little resistance. Councilmember Jim Graham sends out a little note to the MPD-3D list every time a camera goes up or he successfully pushes through some funding for them - but he always adds this little addendum, as if to deflect impending attacks from civil liberty nuts like me. Like from this message last week:
AS [sic] I have said many times, crime cameras have limited utility: they can record evidence of crimes, but, as important, they dislodge embedded crime. Of course–once imbedded crime has been scattered–MPD has got to be ready to give chase. Yet the very act of moving crime has advantages, since what are probably long standing patterns are disrupted. Blocks which have suffered for years due to drug markets and other crimes know what I am talking about. Chief Ramsey has committed to an action plan for just that type of police work for the Third District.
Let’s hope MPD really is ready for this, and let’s hope these statements are not forgotten once they have served their purpose. I fear that the political will to remove them is as ephemeral as the electrons via which I received the email.