As part of its move toward an initial public offering possibly before the end of 2011, PopCap Games is making some of its revenue information public, including the tidbit that Facebook revenues generated a significant portion of its $100 million 2010 revenue.

PopCap Games chief executive David Roberts declined to give specific numbers during a joint interview with Inside Social Games and Inside Mobile Apps, but his press presentation broke down the company’s 2010 revenues to 38% PC download, 34% mobile and 14% online. Roberts said “most” of that 14% came from Facebook, which could mean the the company made around $10 million on Facebook last year. According to our traffic tracking service, AppData, the company has about 16.7 million monthly active users and 4.2 million daily active users as of today. This makes it the #7 game developer in terms of MAU and the #3 in DAU with just two games — Bejeweled Blitz and Zuma Blitz – available on Facebook.

What makes all of this especially interesting is that PopCap games seem to monetize well on Facebook despite its games’ arcade genre categorization. Arcade games generally have smaller average revenue per user margins because the gameplay is so casual and the play sessions are so short. But according to Roberts, when PopCap monetized Bejeweled Blitz on Facebook through the sale of Coins last summer, the game reached $1 million in revenues by August. A slide included with the press kit says that total “social revenue growth” is up to $2.5 million per month.

It’s hard to say exactly what makes PopCap games immune to the monetization woes of other arcade games, but Roberts believes it has to do with how monetization is built into the game. PopCap is known for being “slow” among game developers, taking a long time to develop a game and later iterate features that impact gameplay and Roberts says this makes for a more quality product that people are happy to pay for. An additional factor may be brand recognition; each of PopCap’s franchises (Bejeweled, Zuma, Peggle, etc.) are available on multiple platforms like Xbox Live Arcade or Nintendo DS, which increases the likelihood that players will both see and engage with the games wherever they can find them.

For the moment, Bejeweled and Zuma are the only two PopCap franchises available on Facebook, although the company has been experimenting with its other brands. John Vechy, PopCap co-founder and VP of corporate strategy and development, told us that the company cancelled about three different Facebook versions of Plants vs. Zombies; although a Chinese version exists on SNS RenRen. We were told not to take this as a hint that Plants vs. Zombies would be the next PopCap Facebook game — a bullet point on the PopCap Asia press presentation asserts, “What happens in Asia stays in Asia.”

PopCap Games’ next project from the company’s recently announced 4th & Battery studio, Unpleasant Horse, is due on iOS very soon.