The algorithms for facial recognition have improved a lot in recent years. Here is a company showing a working prototype of a mobile app that recognizes faces and attaches links to social network layers to them:
The prototype was shown last year — but there was a live demo at the Mobile World Congress in Barcelone last week. Obviously the company that also created the polarrose.com service wants to turn this in to a real application.
The implications of this is shown in the video: when looked through the “eyes of the app” people virtually carry logos, brands, name tags and messages around.