It just crossed my mind, a lot of web games would have a pretty easy transition onto the iPhone, mainly b/c a lot of web games use the mouse, that would just be perfect for the iPhone's touchscreen.
I have mixed feelings about adding physical gamepad support to the iPhone, mainly b/c not everyone will have one, and not everyone will want one, lots of people buy the iPhone for anything but gaming.
It'll also make the lives of gaming developers tougher, designing a game for an unknown gamepad can be tricky, each gamepad may have a different button configuration or number of buttons might differ, major headache if you ask me, from a games design standpoint.
It's also extra bulk you have to carry around, if they ever do start selling gamepad addon controls. One of the biggest strengths of iPhone gaming is the fact that it's so convenient, the iPhone is so compact, it's thinner than both the PSP/DS and smaller overall than the PSP.