It seems that some unfortunate who was trying to physically hack open an iPhone in order to modify the hardware to unlock it from AT&T caused it to "explode". The victim explained:
The antenna cover was a bit tricky but eventually it came off. Then we started to open the metal cover (after taking out the 3 screws) and PUFF, up it went in smoke… It literally went up in black smoke. I[t] was so hot that when I tried to pick it up I burnt my fingers. So, this is for shure [sic] the most difficult part of the whole process. I don’t know what he did, as I had just stepped out of the room to fetch something when I heard a scream…they got such a fright. I will post a photo of the iphone… To everybody out there, be carefull….