There is already a hack to get serial communications working through the iPhone’s 30-pin connector, which requires a jailbroken phone. Looking at the the iPhone development website, the 3.0 SDK seems to be a bit friendlier when it comes to communication with 3rd party hardware.
I’m not part of the developer program so can’t dig into any of the technical details of the 3.0 SDK, but I’m wondering if serial support through the physical connector is going to be supported. It says Bluetooth is going to be supported, and that it’s possible to go blutetooth<->serial, but I’m asking about the physical connector specificially.
What I’m considering is an iPhone app which connects to and existing device I have which speaks serial. I’ve never done any iPhone development or hacking.
The 3.0 SDK is still under NDA, so no registered developer is at liberty to talk about it. Just wait one more week, there’s a good chance that the 3.0 SDK will go public at the WWDC keynote on June 8.