I thinks this is a great idea! anything that can replace using paper is much better!
and besides, seeing a picture of the food you’re about to order is nice because we’ve all ordered something that sounded a lot better in the description than what arrived on the plate! I've been to restaurants that are using iPad menus and It upgrades the entire dining experience to a whole new level!! All made by a company named "Conceptic" who has over 1000 installations worldwide. Their iPad menu application is gaining a lot of attention lately:
www.emenu-international.com/iPadMenu