Audio description campaigner Phillip Chalker has started a website that lists the movies available with AD in the Australian iTunes Store. This is something you need to be careful about as the Australian iTunes store has different AD offerings than the US and UK, etc iTunes stores. But the fact they have AD at all is awesome and Phillip deserves thanks for his campaigning on this and other AD accessibility issues. The link to Phillip's website is below. He will update it regularly.
On another note, I've been overseas recently and was very pleased to see audio described movies among the entertainment offerings on Qantas.