http://www.boygeniusreport.com/2010/07/08/iphone-4-catches-fire/
The customer wanted to exchange the iPhone obviously for a new, non-charred unit however the AT&T store in question was out of stock. An Apple Store did confirm to our AT&T connection that this did appear to be a defective USB port and not some sort of user error. Our source went onto say that the phone bezel was extremely hot (obviously), and it slightly burned the customers hand. The USB port in the phone was slightly melted and the cord was badly melted (as is apparent in the pictures).