The problem where the charge indicator light remains amber even though it’s fully charged has returned. I haven’t seen it since the second day I owned the PowerBook.
XBattery might help you determine the actual charge.
Have you tried "re-calibrating" your battery? Drain it down to 0-5% and then fully recharge. It's reported to have helped a few people.
You might also try resetting the Power Manager Unit (PMU). On this model, hold down shift+ctrl+option+power button for 5 seconds. There's no visible sign that you've done this like on other models, but it should work.