Presently, with the 2.5G iPhone you can cancel the data plan, I did. It is still unknown whether you will be required to keep the data plan with the new 3G iPhone (you are required to have it when you walk out of the store). Since AT&T just brought back the ability to cancel your data plan online under your Accounts page, it would be weird if this same page wouldn't apply to the new iPhone. So, why would they bring back this feature 3 weeks ago, if it won't work after next week for the new iPhone. Will they have 2 separate types of accounts for the 2 types of iPhones? We'll find out soon enough, but I bet you will be able to cancel it if you want.