Apple on Friday said it recalled (actually it's an "exchange") every power adapter that shipped with the 3G iPhone. In a statement Apple said:
Apple today announced that under certain conditions the new ultracompact Apple USB power adapter’s metal prongs can break off and remain in a power outlet, creating the risk of electric shock.
Apple has received reports of detached prongs involving a very small percentage of the adapters sold, but no injuries have been reported.
iPhone 3G users need to swap these adapters. In the meantime, you should charge your iPhone 3G via the USB cable, standard Apple USB Power Adapter or third party charger. The rub here is that replacements won't be available until Oct. 10. You can order the redesigned adapters online or exchange it at an Apple store Oct. 10.