Check this out, folks. Some enterprising young hackers have got an IR keyboard working with a non-jailbroken iPhone. With nothing more than $20US worth of parts and the iPhone 2.0 SDK, they built an adapter for the headphone port that talks with a modified version of the audio port modem microcontroller firmware.
Of course, this isn't a rig that my Aunt Ethel is going to run out and buy for her own iPhone, but it's the first time we've seen an external keyboard working with an intact iPhone. Back in the day, my Stowaway keyboard brought my Palm ///e to unknown heights of usefulness. I'd like to experience the same glee with my iPhone.