The photo says it all:
Source: Boy Genius Report
First, the antenna problem. Now, this.
BGR (source) tells the story:
Yes, it’s a fried iPhone 4. Apparently a customer brought the phone into the store to try and get help with it, although it’s pretty evident that the phone is unrepairable. It’s the first time our guy has seen this happen (us too), but the brand new iPhone 4 caught on fire while being hooked up to a computer using the Apple USB cable that accompanied the device.
[...] 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).
Seriously, what's next?