This article provides another example of the "no free lunch" principle as it applies to community wireless. Sprint is having trouble rolling out its WiMax service offering because of backhaul costs (you need fiber to the towers to provide adequate bandwidth) and subscribers are getting about 4 megabits of bandwidth--exactly what I was hearing years ago from knowledgeable wireless experts.
WiMax is an excellent set of technologies that will eventually replace most WiFi, but wireless is only a partial solution for community broadband.