According to AT&T CEO Randall Stephenson, iPad will be a Wi-Fi driven product. "My expectation is that there's not going to be a lot of people out there looking for another subscription," he said.
It makes sense; people who already have an iPhone subscription may be unlikely to go for another subscription, especially since it's not crucial to the iPad experience, which comes in both Wi-Fi and 3G flavors.
But, have you ever actually tried to do some meaningful work (or even casual browsing) using only a Wi-Fi connection when you're on the move? Often, you'll find many Wi-Fi connections available, but they're all password-protected. When you find one, you're not very mobile anymore: sit on a tram, bus, or a subway, and your Wi-Fi is lost, then you have to search for another one. Finally, open Wi-Fi connections are often unsafe, and many users won't dare access or send sensitive data over them.
Being able to fall back to a 3G connection improves your mobile Internet experience tremendously, and the logical question (that no one answered yet) is this: Will iPad users will be able to tether 3G connection from the iPhone? After all, if you're paying for a 3G iPhone subscription, shouldn't you be able to use that connection on another device (bought from the same carrier and the same manufacturer)?