Aiming to boost its own face recognition technology
Facebook is obviously interested in Face.com's facial recognition technology and expertise, even though the social network has its own similar technology. But it's also got billions upon billions of photos that need to be analyzed.
Photos have long been the driving force of Facebook and continue to be hugely important, even though they've mostly been treated as an afterthought.
That's a testament to the implicit power of photos to bring people together, even the rudimentary tools that Facebook provided initially were enough to guarantee its success over other social networks.