The iPhone, like the iPod before it (well, at least since the 3rd-gen iPod, when Apple switched from FireWire), uses a proprietary connector called the dock for charging, syncing, video and audio-out, and multiple other functions. A broad port with 30 pins for many purposes, having a proprietary connector gives Apple a lot of flexibility, but also -- through their licensing program -- a lot of control over who can make peripherals and what can be done with them.
