"Web vigilantes are doing their best to make sure facial recognition technology gets a fair shake in the London riots, though. Just last week, researchers established that off-the-shelf facial recognition technology mixed with Facebook's vast database of photos linked to people's real identities can lead to fairly reliable identification of complete strangers. Digital crime-fighters plan to use the same techniques the researchers used to identify students at Carnegie Mellon University to identify English rioters. On a Google group called London Riots Facial Recognition, a bunch of technophiles are discussing using Face.com's facial recognition API to create a Facebook app that will identify ne'er-do-wells in London."
The concept of facial recognition is increasingly attractive to some crime fighting organizations, but hasn't yet taken hold completely. London police have been posting images form video cameras online to try to get people to identify rioters.