Actually, Macbooks use lithium polymer batteries which are highly explosive when overcharged (http://www.youtube.com/watch?v=0MiM2E6pvfg). So by telling the OS that a battery is not charged when it really is can cause it to explode.
That's a bare LiPo cell wired directly to current— not a good demonstration of how a well-designed battery pack would behave, even one with malicious firmware.
