Erin at Vegan Restaurants Master List is contacting the corporate headquarters of restaurant chains to ask "What's vegan?"
Erin's blog is a great resource for anyone who's vegan (or aspires to be). But it's good reading too for anyone with an interest in seeing how corporations respond to friendly questions from customers and potential customers. The responses range from helpful and well-informed (Chili's) to highly evasive (Jimmy John's).
It's remarkable how little the people who run restaurants sometimes know about what they're serving. A few days ago, when I asked the manager of a Taco Bell if the rice was vegan, she laughed and said she had "no idea."
A related post
Is Jimmy John's bread vegan?