snap crackle and SMOKE

well this is a new one for me...i went to pull down the display for better viewing and the machine shut down...i then pushed the power button to restart and i heard a snap crackle and then a poof of smoke...the machine was still trying to boot but i unplugged imediately and stared in amazement...whatever could of happened???thanks in advance...i am dropping it off to the mac store in seattle on wednesday so i will update when i find out exactly what the cause was...