when i spoke to disney, they said that i would have to have an actual pass when i checked into the resort. i explained that i was buying a voucher and would get the pass after i got there but was coming straight to the resort. they told me that since i would not have a car, i would have to leave my lugguage with bell services and take the bus to the nearest guest services (downtown disney was suggested) and trade the voucher in before i would be allowed to check in.
sounded like a big hassle to me but i am getting the feeling that it is a speech that the reservation people must give. many on these boards have said that they showed their voucher and were able to check in fine and asked to just bring the pass back later. others said that they weren't asked for anything. if you do not have an actual pass at checkin but just the voucher, just be prepared to go to guest services at one of the parks or downtown disney if they ask.