AT&T posts PDF regarding 3G Data Plans for Apple iPad
If you’re going to be an iPad user of AT&T’s 3G Network, then you’ll need to take a look at this PDF.
Click on the above picture to be taken to AT&T’s fact sheet. Here are the highlights: $15 = 250 MB of data per month, and I think if you exceed that amount you’ll have to purchase another $15 data plan and the 30 days will start again. So if you anticipate more than 250 MB, then opt for the $30 per month plan.