in which we used the iPhone Javascript API to capture touch/drag events, and sent them (via a laptop, and then a microcontroller) to a little toy car's transmitter. No SDK use or jailbreaking required at all. However, we had to rely on proprietary Javascript events, and had to include a laptop on ad-hoc wifi to relay the messages. Apple's restrictions certainly lead to major tradeoffs, but we were able to build something pretty neat and accessible regardless.
As a side note, they've locked down both the dock connector and the Bluetooth interface very tightly. Just buying the $99 dev license doesn't allow you to develop for either of those interfaces -- they have a separate "Made for iPod" program for that. The $99 isn't an insurmountable barrier for hobbyists who really want to tinker, but the "Made for iPod" certification probably is. (Some companies are using the audio input/output to hack around this restriction.)
http://www.nerdkits.com/videos/rc_car/
in which we used the iPhone Javascript API to capture touch/drag events, and sent them (via a laptop, and then a microcontroller) to a little toy car's transmitter. No SDK use or jailbreaking required at all. However, we had to rely on proprietary Javascript events, and had to include a laptop on ad-hoc wifi to relay the messages. Apple's restrictions certainly lead to major tradeoffs, but we were able to build something pretty neat and accessible regardless.
As a side note, they've locked down both the dock connector and the Bluetooth interface very tightly. Just buying the $99 dev license doesn't allow you to develop for either of those interfaces -- they have a separate "Made for iPod" program for that. The $99 isn't an insurmountable barrier for hobbyists who really want to tinker, but the "Made for iPod" certification probably is. (Some companies are using the audio input/output to hack around this restriction.)