Here's the thing: that horrifically swollen, completely destroyed battery you're peering at above isn't as rare a sight as it should be. If you'll recall, we've personally covered at least four MacBook Pro battery explosions, and we've also seen a similar amount of volatility over on the PC side. The story behind this one is as follows: a 17-inch (non-unibody) MBP owner was using his machine on a desk (thankfully), when suddenly an odd noise began to increase in volume; following that, the entire machine "jumped up" slightly and turned off, and this battery is to blame. Oh, and if this all-too-commonplace occurrence happens to you next, let's hope you aren't actually using your laptop on your, um, lap.
:p