Last year, I took at look at a Darpa proposal to keep an entire city under watch. The idea was to network together surveillance cameras, and use computer algorithms to watch out for suspicious behavior.But it looks like the city of Chicago may beat Darpa to the punch. "A highly advanced system of video surveillance that Chicago officials plan to install by 2006 will make people here some of the most closely observed in the world," the Times says."Cameras are the equivalent of hundreds of sets of eyes," Mr. Daley said when he unveiled the new project this month. "They're the next best thing to having police officers stationed at every potential trouble spot."Police specialists here can already monitor live footage from about 2,000 surveillance cameras around the city, so the addition of 250 cameras under the mayor's new plan is not a great jump. The way these cameras will be used, however, is an extraordinary technological leap.Sophisticated new computer programs will immediately alert the police whenever anyone viewed by any of the cameras placed at buildings and other structures considered terrorist targets wanders aimlessly in circles, lingers outside a public building, pulls a car onto the shoulder of a highway, or leaves a package and walks away from it. Images of those people will be highlighted in color at the city's central monitoring station, allowing dispatchers to send police officers to the scene immediately.The Times notes that Daley & Co. "designed the system after studying the video surveillance network in London." It's an odd choice. Because the British camera systems' role in reducing crime has been, at best, inconclusive.