FWIW, one of the things I love about my iBook G4 is the battery life. I can usually get > 4 hours, and often >5 hours for casual use with wireless on!The recent report on the MBP leaves it's battery life at <4 hours, so you might guess that the iBook, even if it does use integrated video as the new mini, will probably have less battery life and run hotter than the current G4s.
If battery life is important to you, consider the G4.
I guess the big question is, what do you intend to do with your iBook/MacBook?
B