http://in.news.yahoo.com/photos/a-flying-tray-that-delivers-food-slideshow/
I think its AR Drone delivering sushi at "yo! sushi" restaurant in london

Frightening to think of the injuries that could be caused to the customers.................

My thoughts- Maybe a cheaper segway kind of robot variant(line following) or 3 wheeled preprogrammed robot would be better for such close proximity nonsense, it can be used as the waiters lower body, maybe stabilize the food on a gimbal...
Other better uses for multirotors can be search and rescue, security, perimeter watchdog, first aid, supply drops, and much more sensible areas other than the usual AP. 
that parrot drone wont lift anything heavier, heavy things= more thrust= more air turbulence= food and other stuffs around starts flying too.