OpenFeint has announced that they've reached 25 million users on their social networking service for apps on the App Store. That's an astounding number, and not only does it represent an amazing achievement by the folks at Aurora Feint, but it hints at just how big Apple's official Game Center service will be (whenever they get around to, you know, implementing it). Just for comparison, location networking service Foursquare is still racing to try and hit 3 million users, so in just over a year's time, OpenFeint has picked up many times that number. Those users represent almost a third of the iDevice market and over 85 million devices across 1900 different developers.
The service has also announced that they're bringing out the beta of version 2.5 for developers to implement in their iPhone apps and games. The new version includes a revamped API, which will allow for both turn-based and "action replay" multiplayer (a functionality that Game Center won't yet offer, as far as we know); it's also Game Center compatible, so developers who implement OpenFeint in their games will be able to easily transition to Apple's official service when it comes out (that's what we heard from Jason Citron a little while back, too). OpenFeint 2.5 is in beta right now and will arrive on iPhones later this summer.