You see, if people don't use iPads out of range of their home WiFi networks (some of which AT&T provides) then AT&T doesn't have to worry about keeping up with the demand for faster cellular networks capable of providing lots of data. Obviously, they already can't support their current customer base of iPhone's properly, so if millions of iPad customers sign up, there will be even more complaints.
While this might be wishful thinking (maybe iPad users can just hang out at McDonald's and use AT&T service for free), it would seem it's just typical short sighted AT&T quick profits over long term investment strategy that appears to be Stephenson's policy. Keep profits high, don't invest, push the stock up and…
Escape with a golden parachute? Pocket big bonuses? Whatever Stephenson's plan is, presumably he has an exit strategy before it turns out the iPad is a very mobile device and people aren't going to be willing to accept 3G on it.
Meanwhile, us iPhone users are waiting for our own exit strategy, from AT&T. 4G and WiMax look promising.