Exploding Laptop Batteries

I had the battery on my MacBook rupture to the point where it distorted the cover on the bottom of the case (all fixed by removing the offending battery), but no "boom" type explosion. I'm guessing it overheated as the machine was running 24/7 in a fairly warm room.

I will say kudos to Apple for making something that will fail on the safe side, because batteries store a good amount of energy, and it doesn't take much (heat, puncture) to short them and cause a runaway thermal condition (i.e. boom.)