Starbucks in my area have recently started offering a gluten-free Valencia Orange cake along with their other baked goods, and being as I am a fan of sugar and a fan of baked goods that don't get my kitchen all messy, I picked one up.
Based on the ingredients, the cake seems to be based on almond cakes that are popular throughout the Mediterranean. It's a wise move -- it's always easier to successfully make a dish that's naturally free of the allergens you're trying to avoid than to use "better living through chemistry" to create a taste or texture you otherwise couldn't. As far as other major allergens, the cake includes almonds, eggs, and citrus and mentions peanuts and other tree nuts in a cross-contamination warning on the package. The ingredients include no dairy or soy, though there is no mention of cross-contamination one way or the other for these allergens. And the cakes come pre-wrapped, so there's no chance of cross-contamination in the bakery rack.
I split the cake four ways -- among myself, two non-celiacs, and a non-celiac child who will generally eat anything if it has a sufficient amount of sugar. The verdict? Unanimously positive. The orange flavor could perhaps be a bit stronger, but the texture and moisture level are spot-on.
Allergy-friendliness is a constant request at My Starbucks Idea. Peanut and tree nut-free pastries, dairy-free pastries, or other such cakes and cookies baked in dedicated facilities and packaged to avoid contamination would be great additions to this experiment.