Just saw this over at allears.net
3/2/12 Monorail Service Disruption
Magic Kingdom Monorail: Beginning March 2, the monorail service on the Magic Kingdom Resort and Express routes will be temporarily suspended between 11:30am and 6:00pm. Extra buses and watercraft will be available for transportation. Planned maintenance will be performed during this time. Monorails will continue to operate normally for Extra Magic Hours. The Epcot Monorail will operate normally. This work should be completed by the end of March.