Apple has settled a law suit in which consumers will be paid a cash settlement for failed power supply units which failed prematurely. Apple did not admit fault, but agreed to pay users who paid to have their AC adapters replaced. In addition Apple has setup a website in which to file claims for repayment.
On the web site it states:
The purpose of this website is to inform purchasers of replacement power adapters for certain Apple PowerBook or iBook computers of a class action settlement.
The settlement will provide a cash payment if you purchased certain model Apple PowerBook or iBook computers, the power adapter failed within the first three years following the initial retail purchase of the computer, and you purchased a replacement adapter.
Note: If you previously received a notice relating to replacement power adapters for certain Apple PowerBook and iBook computers, please do not disregard this Notice. Additional computers covered by the settlement have been added since the previous notice.
They also list a way to determine the serial number for your unit to determine if you qualify for the cash payment. Make sure you read the dates when the claim forms must be filed by.