Brazilian police have come up with a system to scan the faces of people in crowded areas, checking them against a central database to see if they're wanted bad-duded. I love this. Truly, these are like the grandpappy of the wearable systems from Snow Crash. It's a set of glasses with a camera fitted to them. The camera can grab 400 faces per second out of a crowd and send them all to a central database. If there's a match, a notifier pops up on a screen and lets the officer know that there is a wanted criminal afoot.