In my case I was running 10.2.8 at the time. Then after running some uninstaller programs for a wireless PC card- I lost my ability to eject my PC cards both manually and through the finder. There are various reports of wallstreet powerbooks losing this ability for various reasons under OSX.
My solution was to reinstall the 10.2.8 again and that reloaded whatever files were required to indentify the cardbus again.