I found an article about PowerBook power adapter dangers this morning including a followup about the problematic design on slashdot.

Personally, I’m amazed at the timing, because this very thing happened to Tamarah’s PowerBook G4 on Friday! She had reported that her PowerBook stopped charging and she was almost out of battery. When I got home I looked at it and plugged it in myself and sure enough, it worked for me, but not for her. She was confused but it was charging, good enough. Then I moved the brick portion of the adapter and sparks started shooting from the cord!!! Based on the photos in the article the breakage was in the exact same spot! Thankfully nothing flamable was around, but the sparks sent Tamarah and I both jumping backward. Without a word we headed off to Fry’s for a new power adapter and opted against buying the Apple replacement. We have AppleCare but they cover everything that breaks except the stuff that actually breaks for us (keyboard, battery, power adapter) so we picked up a new adapter and hid the Apple adapter in the garage.

So, if you have a working power adapter for your PowerBook G4, do your self a favor and replace that bitch before it burns down your house. Pay up your homeowners insurance (or renters) and buy some 3rd party adapter.