I was reading the October 2007 issue of Runner's World last night, and there was an article about tri-athlete Desiree Ficker, and it mentioned she was gluten-free! She has a website where people can ask her questions, and there's a few questions about what to eat on long workouts (this question comes up here all the time!) http://www.desireeficker.com/articles/category/nutrition
The magazine gives a sample of her diet.
Pre-workout breakfast: 2 pieces rice bread with butter or honey, banana, coffee
Post-workout breakfast: berry smoothie with soy milk
Lunch: chicken breast on spinach, tortilla chips
Snack: banana or grapefruit
Dinner: brown rice, fish or chicken, broccoli, carrots, zucchini
Dessert: vanilla soy ice cream