As long as it has not been placed in "shipped" mode (meaning a label generated for it) then yes. Otherwise, no. We did this for my mother when she got the iPhone 4. Hers was not shipped yet and our local store had it in stock so we went to the store and the rep canceled her order so she could then buy it from the store. We did it this way to avoid the risk of someone else buying it before we made it to the store and then losing her preorder also.