Starting June 7th, new AT&T customers with have 2 choices for their mobile data plan, which also includes the iPad:
If you go over your allowed usage, you will be charged at $15 per 200MB on the DataPlus plan, and $10 per GB on the DataPro plan.
If you are currently on an unlimited data plan, you will be able to keep that plan if you want.
AT&T has also confirmed that tethering will be available on the iPhone after the release of the 4.0 OS. Tethering will cost you another $20. The catch though is that you have to switch to the Dataplus plan, and lose your unlimited data plan. $45 ($25 for the Dataplus plan, $20 for the tethering access) to share your iPhone internet to another device would be alright if there wasn’t a 2gig cap on it. I think this will drive customers that really want or need tethering to other phones and carriers with more reasonable rates.
These new plans will offer a cheaper alternative for light users and by restricting the data usage from heavy users, it will help AT&T’s already overloaded 3G network.