High above urban streets, gardeners are raising fruits and vegetables in rooftop gardens, The New York Times reported. Some are simply cultivating plants for the fun of it, others are doing it for the environment. At P.S. 6, an elementary school on New York's Upper East Side, plans are underway to transform one-third of its roof into a vegetables and herb garden, which will supply food for the cafeteria.
http://www.nytimes.com/2009/06/17/dinin ... ref=garden

Many of our high-end hotel restaurants in Dallas have them now.