Electronic Arts confirmed rumors this morning as it acquired Playfish for $300 million in cash and stock. The move gets EA into the social gaming market on Facebook in a big way.

The value of the deal — $275 million in cash, $25 million in stock, and up to $100 million in bonus cash if certain milestones are hit by 2012 — reflects the rapid growth of Playfish over the last couple of years. Playfish is the second-largest developer on Facebook, behind only Zynga. It has more than 60 million monthly active users, according toAppData.

With the deal, EA will become a major player in social games, the hottest part of the game industry and a field dominated by three companies: Zynga, Playdom and Playfish. Playfish will operate with EA Interactive, a division focused on the web and wireless games.

In acquiring Playfish, EA is putting pressure on the market leader Zynga. But in many ways, Playfish may be a better deal. Playfish has been known for creating original titles such as “Who has the biggest brain?” and “Restaurant City.” While these titles resemble older video games, they were new to Facebook and performed consistently well. Zynga, by contrast, has been known for a few hits such as its poker and mob games, which gave Zynga a cash cow that it used to create knock-offs of other hit titles. Zynga’s Cafe World, which many deride as a clone of Restaurant City, launched many months after the Playfish title and shot ahead of it to 28 million monthly active users, compared to Restaurant City’s 18 million users.

The emphasis on doing original and high quality games set Playfish apart and made it more attractive to EA. Playfish also avoided heavy advertising of its games and relied more on word-of-mouth than controversial promotional techniques to spread its games. Even with that conservative strategy, Playfish grew to more than 150 million registered users. Playfish chief executive Kristian Segerstrale noted in a statement that EAi’s entrepreneurial culture was a match for Playfish’s.

“Social gaming, with its emphasis on friends and community, is seeing tremendous growth and this is the right time to invest to strengthen our participation in this space,” said Barry Cottle, senior vice president and general manager of EA Interactive, said in a statement. “EAi has been successfully leading the charge for EA, and with the addition of proven expertise from Playfish, their broad consumer base and strong game brands, we’re moving ahead aggressively in our plans to lead in the category of cross-platform social entertainment.”

The word about the acquisition had been spreading for weeks, but both EA and Playfish executives dismissed them as rumors. Playfish raised $21 million from Accel Partners and Index ventures.