Welp, for all my bragging about how the Mac is a great OS for personal computing, I have found a bug of sorts. My iBook (running OS X 10.2.whatever) gauges how long the battery's going to last on the current battery load per [some unit of time]. If you're burning CDs, then, say, it might predict that a battery that's at 70%+ of full charge is only going to last a few more minutes. This makes the iBook panic and drop into "deep emergency sleep" mode (not the real name, of course -- I hope).

[Update: I clicked the button on the battery and it says I'm almost out of energy, so it might not have been lying. Regardless, I have had it go to sleep before from burning CDs, and I've only burned two and a half on the battery this morning.]