Whether or not Facebook acquires facial recognition services provider Face.com, as rumors say it will, the persistence of the speculation calls attention to the expanding use of the technology in social applications.

Face.com's first app, Photo Finder, allowed Facebook users to search for photos of themselves that others had uploaded. Photo Tagger, which suggests names for people pictured, launched in November 2009. Just over a year later, Facebook licensed Face.com's technology to begin suggesting friends for users to tag.

If Facebook acquires Face.com, it could be motivated by a desire to own, rather than license Face.com's technology or to "acqui-hire" the app maker's team, industry watchers said. Either way, a purchase would seem to point to increased interest in facial recognition.

The technology is now in a "sweet spot," benefitting from better computer visualization algorithms and expanding numbers of people sharing photographs, according to Brian Blau, an analyst at Gartner.

"That has to do with the capabilities of the devices and the critical mass of people putting their faces online," Blau said.

The so-called "computer vision" technology that empowers computers to recognize faces has only recently gotten good enough that consumer-facing companies like Facebook, Apple and Google can support it, according to Apu Kapadia, a computer scientist at the University of Illinois, whose research includes digital privacy issues...