can my at&t tilt data plan work with my iphone 3g?

[Wah?]

if i have an at&t tilt and i have an unlimited data plan on it already and i buy the iphone 3g, would i be able to switch my at&t tilt sim card to the iphone 3g and be able to still use my data plan. or does the iphone 3g require some sort of special kind of data plan

[always better in hawaii]

You will be forced to get the iPhone data plan if you buy the iPhone from AT&T (which is the suggested way to do it).

If you buy the iPhone somewhere else, you're lucky, extremely lucky if it's unlocked so that you can use it on AT&T.

Worst scenario? Buy the iPhone from AT&T and ask them to switch to an iPhone data plan. Since you're not ending your service, they should do it with no problem.