TimesOnline warns that iPhone 3G owners will be able to rack up large wireless bills faster than ever. While the UK carrier for the Apple iPhone offers an unlimited data plan, this only applies when you are located in the UK. Once you travel abroad, the cost to download 1MB of data can be as high as £6/megabyte (~$12 US). This means an average BBC iPlayer program could cost as much as £1,800 when roaming in the U.S.
Of course, this is true for all mobile phones, but iPhone users do tend to take more advantage of their data plans. A number of stories emerged after the introduction of the original iPhone about inadvertently large roaming bills.
Fortunately, the iPhone firmware now allows you to turn data roaming off, which avoids accidentally walking into this problem.”
(Via macrumors )