Recognizr, an application that lets users point a smart phone at a stranger and immediately learn about them -- combining computer vision, cloud computing, facial recognition, social networking, and augmented reality -- has been developed by The Astonishing Tribe (TAT), a Swedish mobile software and design firm.

A user points the phone's camera at someone nearby. Software then detects the subject's face and creates a unique signature by combining measurements of facial features and building a 3-D model. This signature is sent to a server where it's compared to others stored in a database. Providing the subject has opted in to the service and uploaded a photo and profile of themselves, the server then sends back that person's name along with links to their profile on several social networking sites, including Twitter or Facebook.

(Source: http://www.technologyreview.com/computing/24639/?a=f)