NEW ORLEANS, LA -- Design professionals from across North America and beyond have gathered in New Orleans at the AIA 2011 National Convention and Expo, which carries the theme: "Regional Design REVOLUTION: ecology matters."    AIA Expo 2011, which runs from May 12 to 14, introduces attendees to more than 800 exhibitors to discover new products, technologies and services. The exposition also houses special display areas, educational opportunities, pavilions and association offerings.   For the past dozen years, the exposition floor at AIA Expo has included a designated Stone and Tile Pavilion, which includes a broad range of stone and tile products as well as installation materials. Sponsored by Stone World and Contemporary Stone & Tile Design magazines, the pavilion includes displays from Tile and Stone of Spain, Ceramic Tiles of Italy, the Natural Stone Council, Marmomacc and more.