Facial recognition has been a growing trend in social media for quite some time, and now dozens law enforcement agencies in several states are finding a better use for the technology. As of September hundreds of police officers will  be carrying a device developed by BI2 Technologies that attaches itself to their iPhone and will let them instantly compare a person with a criminal record database. The gizmo uses facial recognition technology, collects fingerprints, and there’s more.

“With the device, which attaches to an iPhone, an officer can snap a picture of a face from up to five feet away, or scan a person’s irises from up to six inches away, and do an immediate search to see if there is a match with a database of people with criminal records.”

It was only a matter of time that facial recognition would be used by low enforcement agencies. Tech companies have been refining the technology for quite some time now, and among them is Viewdle. The mobile service scans an individual’s face and tags their name to that photo. It has become so popular in fact that it raised $10 million in funding from Best Buy, BlackBerry, Qualcomm, and Anthem Venture Partner.

It’s not just relatively small services that employ facial recognition. Facebook launched Tag Suggestions a while back; a new feature that lets users group photos featuring a similar place and automatically tag them with that particular friend’s name. The social network leverages Face.com’s Phototagger and Photo Finder products, a startup that was founded in 2007 and also raised funding recently. Rhodium and Yandex invested $4.3 million in the facial recognition service.

Lastly, Blink!, a security product for Windows 7 and Vista, is another example of this kind of technology being used.

Facial recognition has a very practical use from more aspects than one, but it also raises some privacy concerns. After all, the fact we’re all getting much easier to identity leaves room for exploitation.