It's been about ten day in Sicily so far, so I thought it was time to share my experiences of eating gluten-free (for the first time in Italy).
Palermo: I bought a box of gluten-free cracker-bread at a pharmacy. The B&B owner went to the gluten-free bakery (!) and bought several breakfast pastries for me - jam and chocolate-filled cornetti, and an apple and cream-filled Danish. I could have been fine with the breakfast offerings without the pastries: corn cereal, yogurt, meat, cheese, fresh fruit. At a touristy restaurant for lunch, complete with photos of food and a €20, 3-course tourist menu, the chef came out to explain that he would grill the chicken breast on the menu instead of reading and frying it - €8, with a small salad.
Monreale: at Giardino dell'Arancia, the waiter pointed out gluten-free options on the regular menu, then disappeared for a few minutes and came back with a little loaf of gluten-free bread, still warm. Strips of beef cooked in balsamic sauce with a side order of spinach, less than €15.
Selinunte: a very small town but every waiter knew what was gluten-free. Grilled fish, caught that morning, with grilled potato and zucchini slices, seasoned with salt, lemon and olive oil. Selection of fresh sardines and bluefish, about €17.
Agrigento: brought my box of cracker-bread to breakfast and piled home-made jam and fresh cheese on it. Delicious. I ordered caponata for a starter and had the first gluten-free pasta of the trip, much better than the brands I've tried in the U.S., with a ground pistachio sauce. The restaurant next door to my hotel has a gluten-free dessert tart, can't wait!
Tip: Many pharmacies stock gluten-free items, but if they don't, they can order something for you for the next day, or later the same day. Supermarkets also have gluten-free sections. Favorite tip: natural food stores ("bio") stock all kinds of special diet items, often easier to find than pharmacies with gluten-free products in stock.
If this is helpful, I will continue with updates.