USAirways was in a test phase for the return to MCO. I'm not 100% sure it's an option at all resorts. Perhaps someone knows what the story is.
In any case...anyone flying out of MCO on a 'participating airline'..Airtran, Alaska, American, Continental, Delta, Jetblue, Northwest, United...is able to check their luggage right at the resort. This service is provided by RAC (remote airline checkin). For those who may have checked bags that will be charged, per the airlines official policy, you will have to call the BAGGS phone number and pay, via credit card, what the addtl charges are. Then you will be able to check your bags with RAC. RAC is not set up yet to accept payments of any kind. When you get to WDW you will be given the number to call.
Evidently, they have some way of discerning whether or not there is an addtl charge based on the ticket purchase date.