Evan DiBiase has done a bit more detective work after having found YouTube strings in Apple's iTunes protocol. Now he's uncovered references to the iPhone in Apple's secureBag, specifically references to an iPhone Registration page. Unfortunately the page, which uses secure https, doesn't seem to work as yet. And the other references in storeBag and secureBag produce unhelpful responses such as the one shown here.
Just for the sake of completion, I also searched through the strings in iTunes 7.2 but found nothing new to report.