Assuming 600,000 iPhones sold thus far, and assuming a certain percentage are new contracts vs. existing, you're looking at $125 million (conservatively) or more over the life of a 24 month contract for all those phones, not to mention the millions more phones they'll sell over the coming year.
Of course, that doesn't include the $400+ million is sales of just the iPhone unit itself so far. Costs $200 to produce, sell for $600? Oh yeah ...
As far as sales in the future, when 32% of people surveyed said they'd buy one, that's easily 50 MILLION people with an iPhone in their pocket .. and that doesn't even count overseas sales.
And who says Apple doesn't know what it's doing?