zoning government data mobile app

I am imagining a mobile app that lets you walk around NYC, and letting your device use your location, display zoning information for the building lot(s) at the address or location.

Developers already walk around the city, investigating under-developed sites and (when the market is right) calculating total square footage allowed under zoning.

I don't know if zoning information has been coded with addresses in any public data source.

But this could be useful for a lot of people. Would be interested to hear from local NYC tech folks who might have thought any of this through?