That's right. The iPhone has a rumble pack.
It's a detail that's been pretty much neglected across the board in discussion of the iPhone's merit as a gaming platform, leading up to the launch of the iTunes App Store. But as anyone who's downloaded and played Pangea's Cro-Mag Rally on the iPhone can attest, the device is capable of basic haptic feedback thanks to the vibrate feature used primarily by the phone side of the iPhone.
Most modern consoles are capable of some form of rumble / vibration, at least as an option. It's great to see that the iPhone SDK has opened this up to developers. Just as skidding across tracks in the mud in Sega Rally Revo on the XBOX 360 wouldn't be nearly as satisfying without the rumble, so too would collisions in Cro-Mag Rally be less jarring without that in-hand jostle.
Unfortunately the iPod touch lacks a vibration feature, but we still hope to see rumble widely implemented in iPhone platform games (hopefully as an option that can be turned off to save battery life). The Sony PSP does not support rumble of any sort. On the Nintendo DS, it's available via option pack in game that support it. Having it built-in to Apple's flagship mobile device is a definite feather-in-the-cap to the iPhone as a mobile console.