Delta used to but no more.
Now you have to pay their change fee.
So Delta has rejoined the group of airlines where it is recommended you wait for a fare war instead of buy at their everyday low price (except for Thanksgiving, Christmas, etc.).
Disney hints:
http://members.aol.com/ajaynejr/disney.htm
For Delta the "fare ware" booking class is T, the "everyday low price in limited supply" is U. The next step up is L.