We shipped a ton of stuff, and it worked perfectly.
About a week and a half beforehand, we sent a big box of ceremony and reception items, including our favors, to the first resort we stayed in. We also bought bottled water at Costco.com and had that shipped to two of our other resorts. In all cases, the items arrived in plenty of time and were easy to get from Bell Services.
For the ceremony/reception items that were left over, we packed them back in the orignial box and drove them to UPS in Celebration to ship home. I've heard you can also ship packages home from your Disney resort, and I think there may be a FedEx or UPS near Downtown Disney.... let's see...
FedEx Kinko's: 12181 S Apopka Vineland Road
Mail Boxes Etc.: 12179 S Apopka Vineland Road
The UPS Store: 8131 Vineland Ave