I'm sure this is just the first of many and hopefully some of them adopt dual analoge sticks like the PS Vita. This image below is apparently a leaked photo of a Logitech iPhone 5 gamepad dock.
Although Rockstar hasn't formally announced the iPhone version, I think it's verys safe to say it will be in the way. If anything this will add serious cred to any version of GTA V that is brought over to iOS. Essentially this means that there are going to be many many more gamepads and joysticks made specifically for gaming on your mobile device. Essentially this means that using a real controller on an iOS device is going to become a lot more common and a lot more mainstream. Update: The best news lately regarding GTA on your iPhone or iPad or iPod, is that the new version of iOS is going to have a new and improved gamepad support.
Guide To Playing GTA 5 iPhone, iPad and iPod Games