I just received gluten free information for some of the parks for our next trip so I'll try to hit the highlights.
Note that WDW considers anything with no gluten added to be gluten free. They have less concern than I personally do about cross contamination, but that's because I have extremely low tolerance for cross contamination. Everyone is different and a lot of people are very comfortable with the products provided and the way that WDW handles things like buffets.
At Magic Kingdom:
We usually high Cosmic Ray's. On our last trip they told us that they used dedicated fryers, but the current list says:
Rotisserie Chicken
Fries done in an oven
hot dog/hamburger/grilled chicken on EnerG Foods buns - Note that these are probably the Seattle Brown buns, which I really like, but they look like whole wheat bread, not like white bread.
Other highlights from magic kingdom are:
dole whip, Amy's Gluten free pizza available at Pinocchio Village Haus, Gluten free Ice cream at the Plaza Ice Cream Parlor, soft serve and an assortment of ice cream bars including Mickey Bars. Main Street Bakery also has a few gluten/dairy free snacks like brownies, chocolate chip cookies and crispy rice treats.
Mickey bars used to be considered gluten free because the same vat of dipping chocolate that was used for dipping Mickey bars also dipped gluten-containing bars. I don't know if that cross-contamination no longer occurs or if WDW has just stopped considering it an issue.
At Animal Kingdom we really like Tusker House. I haven't gotten the AK/MGM no gluten added sheets yet, but I do have a short list of specialty foods for MGM/AK.
Pizzafari and Pizza Planet have the Amy's gluten free pizza
And there are gluten free brownies available at Beastly Bazaar and The Beverly Sunset.
At Epcot your best bet is usually to hit Liberty Inn. They have dogs/burgers/mac and cheese (Amy's), Pizza (Amy's), Baked fries or potatoes with advanced notice, Chocoalte chip cookies and brownies.
Sunshine Seasons can do rice pasta or dinner rolls with advanced notice and has some pamela's cookies and brownies from an unidentified source.
Generally available at TS locations are:
bob's red mill brownies, biscuits, pancake mix, mighty tasty hot cereal
Tinkyada or Mrs Leepers brown rice pasta
Amy's mac and cheese, or gluten free pizza
Ancient Harvest Quinoa/Corn Macaroni
Van's gluten free waffles
San-J tamari
Ener-G seattle brown buns, brown rice bread, tapioca pizza shells, and tapioca rolls
Good Luck!