I wonder if institutions with lawns would lease these them to be used for cold frame agriculture (see http://localecologist.blogspot.com/2009/09/what-happened-to-grow-cook-eat-learn.html).
My comment was inspired by the Grow, Cook, Eat, Learn (GCEL) project of the NYU Graduate Program in Food Studies and the Steinhardt School of Culture, Education, and Human Development. The GCEL greenhouses or wooden cold frame boxes are located on one of two unused, university-owned lots between the Washington Square Village apartments. (Why not install greenhouses on both lawn areas?) This spring the greenhouses are full of leafy greens.
I could imagine shovel-ready greenhouses (pushcart style and/or hitchable to a bicycle) being installed in other underused spaces throughout the city -- for food, for wildlife habitat, for viewing. Interested in a collaboration? Email us at info(at)localecology.org.