This excerpt taken from the AAPL DEF 14A filed Apr 16, 2007.
Termination of Service. In general, if a non-employee director ceases to be a member of the Board, the directors options will be exercisable by the director for a period of 90 days, to the extent vested at the time of termination of service. If a non-employee directors service on the Board terminates by reason of the directors death, the directors vested options will remain outstanding and the directors beneficiary may exercise the options at any time through the third anniversary of the directors death. If a non-employee director is removed from the Board for cause (as determined by the Board in accordance with the Companys by-laws), all of the directors options, whether or not vested, will immediately be forfeited.