Although USB is theoretically 500mA per port, the battery charging standard increases this, and many motherboards and hubs go for the "ganged" over-current approach, so any one port can actually pull (# of ports)*500mA to run those HDDs, Christmas trees, cup warmers and vacuum cleaners.
well, thats what happens when you hold the iphone wrong!
actio, reactio... as easys as that. guys, you cant blame god jobs for this... he told you in advance.
Around 5 or so years ago, I melted the top of my Zen Micro MP3 player because of a faulty USB port on a PC I built. The player got extremely hot and then the top corner where the USB connector is melted and collapsed on itself. The USB header on the motherboard was connected wrong and sending out way too much current I guess. Nothing caught on fire, but the damage still looked kinda cool.