Magical Express is available to all WDW resort guests. You will need to make arrangements thru MS for stays reserved using points. The shuttle is available in both directions regardless what airline is used, but guests traveling on selected airlines will be able to check bags when they depart for MCO and their luggage will be delivered to their resort without having to wait at the bag carousel. On the return trip, those guests can check their bags right at their resort and claim them when they reach their destination airport.
For those guests not flying with one of the selected airlines, you may still use the service, but won't have access to the special luggage handling. Arrangements still need to be made in advance - you won't be able to just decided to use the service when you arrive at MCO. If you are changing resorts while at WDW, you will still be able to use the Magic Express.
Give MS a call and let them assist with the details. (The service begins on 05/05/05.)