Dating site titans OkCupid and Match.com have hooked up today — as Match.com, an operating business of IAC, has acquired the other site for $50 million in cash, plus future payments depending on performance.

OkCupid, an increasingly popular site, generates most of its revenues through advertising (it's mostly free to use — making it popular among members who are strapped for cash), and, according to a release, it has been the fastest growing dating site in the advertising-supported bracket this year. Therefore, we can see how it would be attractive to Match.com, which is — for its part — a paid service.

"We know that many people who start out on advertising-based sites ultimately develop an appetite for the broader feature set and more committed community, which subscription sites like Match.com and Chemistry.com offer, creating a true complimentary relationship between our various business models," says Greg Blatt, CEO of IAC.

"2010 saw record growth both for Match and OkCupid, and we believe coordinating the adjacent business models will help fuel continued growth for both."

OkCupid co-founder and CEO Sam Yagan will stay on at the site to run operations. We've reached out to him for further comment, and will update this post when we know more about how this merger will play out.