Google has filed a patent for Facial Recognition With Social Network Aiding.
The patent abstract describes facial recognition searches for "one or more likely names" of the people in the image. After this visual query has "potentially" matched one or more personal identifiers for each person, it will scour "communications applications, social networking applications, calendar applications, and collaborative applications" to create a list of possible identities for each person.
The patent description also mentions that if the photo is tagged with a person's name, "that picture might be used in future facial recognition queries to recognize the person."
Theoretically, a stranger could take a picture of you, then use this technology to find out who you are. Finding people will become a lot easier. But so will protecting your identity.
You can view the patent by clicking here.