I've actually been curious about this as well. Good to know, thanks! But here's some other battery questions:
-Do iPod's have charge memory? Say, if I don't charge it all the way then will it remember that charge and never charge fully again?
-Is it safe for my iPod if I use it while it's charging? Say, in the car with a charge adapter, it'd be so nice to have music and not worry about losing battery life.