My TiPB 1Ghz's battery was performing poorly all of a sudden, with less than 70 minutes of life and a messed up power indicator. After trying the PRAM and power manager resets to no avail, I called Apple yesterday afternoon, about 3pm EST. They promptly sent a new battery.
TODAY the battery arrived, 26 hours after I picked up the phone. I'm conditioning the new battery right now and all is well--the old battery goes back in the same box.
I'm noting this because I never realized how fast & efficient exchanges were for batteries--in fact, AppleCare pays for itself over 3 years, as I find Li-on batteries become worthless between 12 and 24 months. Since a new battery costs $129 it doesn't take a genius to see that AppleCare works out well for laptops.
So, if your battery life is dropping off the bottom end get your AppleCare extended...and remember that any NEW battery you buy is covered for 1 year, in case you need to do the same.
Finally I just wanted to give props to Apple--that was awesome turnaround.