After about a month of speculation, Facebook has finally announced its acquisition of Israeli facial recognition technology Face.com.

We’ve heard from multiple sources that the acquisition price was around $100m, with others reporting that the price was between $80m-$100m. (Update: We’re now hearing from a source familiar with the matter that the price was between $55 and $60 million, and that it was a mix of cash and stock. The exact value of the deal will be changing depending on the price of Facebook’s stock.) This is absolutely not an acqui-hire, as Facebook will be taking full advantage of the company’s technology and the advancements it’s made on mobile — perhaps to finally include mobile tagging options for photos.

As Face.com’s speciality is mobile facial recogition, it could potentially allow you to upload a photo to Facebook while on the go, instantly receive suggestions of whom to tag, and confirm the tags with one click.

This is important to Facebook because right now there’s probably a ton of untagged mobile photos getting posted. Those are lost opportunities for engagement because when you get notified that you’ve been tagged in a photo, you probably visit Facebook immediately to check it. These tags also help Facebook understand who a photo is relevant to, so it can feature it in the news feeds of your closest friends.

Face.com’s blog post about the acquisition included a big shout out to third-party developers. “We love you guys, and the plan is to continue to support our developer community.” Facebook could create some sort of API or otherwise allow app developers to build in Face.com’s facial recognition…as long as they integrated with Facebook and let users share content back to it.

The $1 billion Instagram purchase made it obvious that Facebook sees mobile photos and the communities that share them as critical to its future. Once that acquisition closes, Facebook could even port Face.com’s facial recognition to Instagram.

With Instagram and Facebook Camera on the front end and Face.com on the back, Mark Zuckerberg has the arsenal he needs to win the war for mobile photos.