The New York City Taxi and Limousine Commission approved a program where a cellular telephone service provider will equip NYC taxis with devices that will help locate dead zones. Since taxis go pretty much everywhere in Manhattan (south of 120th Street, that is; sorry, black people!), they should be able to collect fairly comprehensive data.
The one problem with this: taxis never got into my old apartment on the 3rd floor of 539 West 112th St. when I lived there. I couldn’t even get one bar in there! Friggin’ T-Mobile.