Social game developer Zynga says it now has 10 million daily active users across all the platforms it serves, including Facebook -- where it claims the spot of number one app developer.

Zynga's games, including Texas Hold'Em Poker, Mafia Wars, YoVille and Scramble, are served across other social networks including MySpace, Bebo, Hi5, Friendster, Tagged and Yahoo!, as well as on the iPhone.

San Francisco-based Zynga claims 40,819,426 monthly active users according to official stat tracker AllFacebook, and 40,483,500 monthly active users on metrics measurer AppData, and says it "continues to experience substantial growth."

Just last month, the venture-funded company hired two new execs, one to head up the company's initiatives further into iPhone development, and the other to lead a new internal studio.

"To think that a city the size of London is playing our games on a daily basis is incredible," says Zynga CEO Mark Pincus. "Our growth is a testament to the talents of Zynga game developers and their dedication to making fun and social games that everyone loves."

"The momentum we’re seeing indicates that the social gaming space is as significant as we expected it to be and that our games are touching the lives of people all over the world."