Yeah, there's no doubt that iPhone is becoming a popular gaming platform among mobile users now. There are at least two reasons: (1) the statistics of iPhones  sold and  games apps on the App Store; and (2) the latest features on the device's OS which enriches the upcoming gaming development.

As Venture Beat wrote:

The company announced this morning that it has sold more than 30 million iPhones and iPod Touch products. And there are now more than 25,000 applications available for download on those devices, including over 6,000 games by 50,000 developers.

Another reason is the company are now adding peer-to-peer connectivity, which is suitable for developing game apps. iPhone Buzz explained that:

...peer to peer connectivity with new APIs include tools to bring up nearby iPhones or iPod touches that would automatically identify running apps and create an instant IP connection with existing Bonjour technology, wireless over Bluetooth. A technology suitable for game apps but Apple says it works for any peer to peer app with quick fire connection without the need of Bluetooth pairing or typing in a password.

In another news, a developer is working on the next game project to enable iPhone gamers to take on PC users who play the popular strategy game.