The current arrangement with Orlando International Airport is through 2011, but there's no reason to believe that Magical Express won't eventually be extended beyond 2011.
All Disney-operated resorts at WDW are served by Magical Express, and they all have Resort Airline Check-in (RAC) counters. The airlines don't have their own employees at any of the resorts, but the RAC counter provides boarding passes and luggage check-in for RAC-participating airlines. See the sticky item, "Disney's Magical Express - What 'Participating Airline' Really Means!" near the top of the DIS Transportation Board thread list for more details.