Installing a city-wide WiFi network (aka municipal WiFi) from scratch is commercially not viable. New examples of this evidence pop up everywhere: Earthlink backing out of the San Francisco project, Chicago’s WiFi project canceled, etc. The top-down commercial solution with huge capital expenditures will never fly and the tax-payers are usually paying a high price for these failures.
On the other hand, you can find everywhere you go 4, 5 or more networks available around you. If people would share their network using Whisher, you’d get  “Free Municipal Wifi” without spending extra on infrastructure. Certainly a model worth trying.