The CEO of AT&T, Randall Stephenson, thinks that the iPad will not have that many new 3G subscriptions.  He thinks that most people will live with Wi-Fi only.

I think that this will be true. Most people are not going to pay the crazy prices that AT&T is charging for 3G data.

250MB of data will cost you $14.99/month.  This will be used up very fast.  Some of the more popular iPhone apps are larger than 250MB in data. That being said I am sure there will be very few who choose this option.

Unlimited data will cost you $29.99/month. This is more reasonable, considering on average high speed internet is around that price. But for people who are already paying for a data plan with their iPhone or other smartphone, there is no way they will want to pay another $30 for something they already have.