So does anyone know if there's a conversion chip in there or whether the standard iPhone connector has a serial pin on it. I seem to remember someone hooking up a GPS to the iPhone 2 and plugging serial straight on. There are already a number of breakout plugs out there, so I'd be surprised if this opens up radical new innovation.
As a side note, other people have used the audio jack for I/O, like the iPhly Remote Control or Square