Why is there no iPhone Bluetooth keyboard?

For what's essentially a minicomputer, a compact external keyboard would seem like a simple and logical accessory and would be especially appealing to those who haven't mastered--or aren't comfortable--typing on the iPhone's virtual keyboard, as good as it is. Travel-friendly, fold-up keyboards are available for the old Palm Pilots and Treos, but a quick search on Google reveals precious little on iPhone keyboards.

Way back in January 2008, Macworld wrote up some notes from the now-defunct Macworld Expo under the headline, "A Bluetooth keyboard for the iPhone?" The article referenced the small MacAlly BTKeyMini Bluetooth keyboard ($100). At the time, MacAlly reps claimed that when the BTKeyMini arrived in March of 2008, it would be compatible with the iPhone. But alas, Apple has never provided Bluetooth keyboard drivers for the iPhone and the BTKeyMini has never shipped