Today Apple released a patch for specific 15" PowerBooks that addresses certain debilitating battery issues. The patch information includes some of the following:
"This update aids the 15-inch Aluminum PowerBook battery in performing at full capacity...This firmware update is required to keep your battery life up to specification, may recover battery life in some batteries that have developed short run times, and in some cases can recover batteries that are not recognized by the system."
The 400 kb patch can be downloaded from Apple"s website or if it affects your PowerBook, from the Software Update dialog.