It is called the bus- on-demand system. Not clear whether it is now what it was planned to be, but basically you should first assume bus system is same as before. The changes are mainly for park trips. We have seen it mostly at the parks rather than at the resorts, but basically if there is crowd at one stop at a park getting stacked up they will reroute a bus which really has no one to take. It is done by a CM watching the area with a two-way radio. Also, it seemed as if they had more busses at park closing time than usual (possibly borrowing some from a park not yet closed). It is supposed to be that way for buses picking up at resorts too (for example if in morning a resort has huge waiting line, they may take a bus or busses from elsewhere that have few riders;however, when we were there resort pick up did not seem any different to us). It apparently applies to boats also. When there for MGM park closing time this summer found there were boats stacked up one after another to take people back to Epcot resorts, apparently they take the boats from inside Epcot after it closes and add them to that MGM run and also make sure all boats are at MGM, and not out making other stops, at park closing (in prior years you always seemed to wait an eternity for a boat from MGM at closing).
