Facebook continues its prowl for photo properties, snapping up face recognition company face.com. The deal is designed to bring face.com's face recognition photo tagging capabilities in-house for the social networking juggernaut. For Facebook, the face.com deal is the second photo-related acquisition it's announced in the past several months and provides a good takeaway for developers working in the digital photo space. You may soon find your company acquired by Facebook in the very near future, if users are flocking to your service in the millions or Facebook is currently a user of your technology. The latter was the case for face.com. Facebook had been a user of its technology for the past two years, says the New York Times. And in the case of Instagram, which Facebook acquired for $1 billion earlier this year, it had generated millions of users in short order. Photos are key to Facebook's future. The Times notes users upload an estimated 300 million pictures per day. And that user engagement is what keeps the site sticky, something advertisers love. Advertisers, of course, bring advertising revenue, which keeps the lights on at Facebook. So, don't be surprised to see Facebook making more of these photo-related acquisitions in the future. If you see Mark Zuckerberg trolling around in your hallways, it may be time to pack your desk. Related Links