Facebook does not tag people in photos automatically, but prompts users to tag friends that the facial recognition system recognizes. The service is opt-out in Facebook's security settings as opposed to opt-in. That aspect of the facial recognition feature and Facebook's approach to privacy altogether is what bothers privacy and security advocates like Sophos.
"Unfortunately, once again, Facebook seems to be sharing personal information by default," Graham Cluley wrote on the Sophos company blog, Naked Security. "Many people feel distinctly uncomfortable about a site like Facebook learning what they look like, and using that information without their permission."
Cluley wrote an open letter to Facebook in April this year, calling for the company to go to a "privacy by default" doctrine as opposed to a privacy via opt-out policy, which Facebook currently employs for much of its information.
Cluley also does not think that most people are mentally equipped to handle the long and sometimes confusing Facebook privacy settings.
"Most Facebook users still don't know how to set their privacy options safely, finding the whole system confusing," Cluley wrote. "It's even harder though to keep control when Facebook changes the settings without your knowledge."
When Facebook unveiled facial recognition last year, it was uploading 100 million pictures to the site a day, with a good portion of those included people (who are likely also Facebook users). Companies like Viewdle and ActiveSymbols are bringing facial recognition applications to smartphones. Divvyshot and founder Sam Odio were acquired by Facebook to help institute its facial recognition program.
For its part, Google chairman and former CEO, Eric Schmidt has said that Google will never get in to the facial recognition game. That has not stopped developers from building facial recognition into Android, such as the application Recognizr.
If you are concerned about facial recognition from Facebook, you can go into your privacy settings and change them. Click "Privacy settings" --> "Customize settings" --> "Things others share" --> "Suggest photos of me to friends" --> "Edit settings" and disable.