Killer App for the iPhone

Can everybody be blind to the obvious? The iPhone has a microphone and a (somewhat simplified) operating system, together with a new -- and not universally admired -- input system for text. So it should be clear that the most valuable new software for this device (what would be a KILLER APP in fact) would be DICTATION software, perhaps like ViaVoice or iListen, but hopefully, more efficient. A user could then dictate, rather than type, an outgoing Email, pick that up on his or her computer, and then file it for storage, print it, whatever. That would almost make the device a true pocket computer.