It seems like every month a new gadget goes up in flames. This month it's an iPod nano that was caught exploding while being charged via a PC. The owner says that the force sent his iPod flying to the ground, where it started smoking and sparking until it was unplugged. Unfortunately, the iPod was out of warranty, so the owner wasn't able to get an immediate replacement. I've had my iPod Nano for a long time now and never has it heated up, so we have to take this one with a grain of salt, but you can never be too wary when charging your gadgets.
This actually happened to me over a year ago with my first generation iPod Nano. It started smoking and went dead when I was charging it on my new Monster iCarPlay. I brought it to the Apple Store expecting them to deny warranty repair and refer me to Monster to get the issue resolved, but they actually replaced it stating that the iCarPlay is an approved iPod accessory and they even supply the connector for it, so it would not void the warranty. Monster denied it was their fault and after many calls, finally let me send the product back to them for "testing." They replaced the iCarPlay with a brand new one and refused to tell me what their "test" concluded.