Slide To Play reports that the company is working with big publishers and indie developers alike, with varying pricing models according to their situations.
The company's platform, which is used for console titles including Grand Theft Auto IV, will allow real-time multiplayer, as well as leaderboards, buddy lists, profiles, matchmaking and cross-platform messaging.
GameSpy signalled its intentions last year, in an interview with PocketGamer.biz.
""We've not traditionally been in the mobile space but we are very excited about iPhone," director of technology Todd Northcutt told us.
"We've always supported gaming on the Mac even though the audience was small, so the combination of the iPhone's memory, processor and screen, plus the potential of the App Store, is great."
However, GameSpy will face competition on iPhone from platforms like OpenFeint and Agon Online.