iPhone gaming has certainly accelerated in the last year or so, and iOS in general has seen a boost from iPod Touch and iPad as well. The numbers are impressive, as new research from Newzoo and Distimo (an App Store analytics firm) shows that games now represent the largest single App-category on Apple App Stores, and account for half of the downloads of both free and paid Apps.
That's a crazy high number. I'm thinking most of those are free games.