I've been using my Powerbook for over a year and have replaced the battery after a year, because the original battery couldn't hold much of a charge after a year. I won't go into all the heat issues related to my Powerbook, because I love the operating system. Mine is an original 15"er that still has the "white spots" because I use it daily and haven't had time to send it back for repairs. I plan to do so when I have the time- whenever that will be I don't know.
HOWEVER, I just found out that the replacement battery I bought a few months ago is in the official recall! This is a battery I bought at the Apple Ginza store here in Tokyo.
If you are an Apple iBook or Powerbook user, please, please, please check to make sure that your battery isn't in the recall.
15-inch PowerBook G4 Battery Exchange Program
Apple - Support - iBook G4 and PowerBook G4 Battery Exchange Program - FAQ
They seem to keep having this same problem, don't they? Didn't they have a whole "Powerbooks catching fire" from batteries a couple of years ago?