If you are curious about how Apple kept the iPhone plans secret for so long, you should check out this Fortune article:

Apple, legendary for the ferocity with which it safeguards new product announcements, had extraordinary challenges in keeping the iPhone under wraps for 30 months. Besides involving Cingular, Google and Yahoo, not to mention the unnamed Asian manufacturer, the project touched nearly every department within Apple itself, Jobs said, more so than in any previous Apple creation.

Via Lost Remote