Your Face Is Not a Bar Code
Phil Agre has a solid essay opposing automatic face recognition systems in public areas. These uses are only going to increase, because the technology is cheap (enough) and appealing to authorities everywhere; it's good to have some arguments to hand for opposing the spread of the cameras.
A security guard recognises a criminal from a mug shot on one of his cameras. He might be right, or mistaken. He'll have to check to be sure.
A piece of software flags a person as a criminal. It might be right or mistaken. It will have to let the security guard check it out to be sure.
The only difference is now one guard can handle more cameras better. The same with finger print software. You can check more fingerprints faster. The crime labs have used those for years. A human eye must still be the ultimate authority, the computer narrows the field a bit.
-Bocaj