Technocrat [1] has an article [2] about wireless networks and the ISPs that are implementing them. consume.net, [3] The Eugene Free Community Network, [4] SFLan, [5] and SeattleWireless [6] are a few of the ISPs in the States working on providing this technology.
And MIT [7] is working on The Grid Ad Hoc Mobile Networking Protocol [8] to help route all this new wireless technology.
I just wished South Florida wasn't so darned flat! It's hard to get wireless networks going with a lack of hills (or mountains) and tall buildings.
[1] http://www.technocrat.net/
[2] http://technocrat.net/968524370/index_html
[6] http://www.seattlewireless.net/