I'm afraid, that your AP operator could get shut down like every other ISP, in case of real emergency (think big crisis and martial law). Independence from "big brother(s)" is key think in this thread - which, BTW, evolved voice-only transfer, into data-transfer of any type (after all, voice send through electronic is a type of data...).

Nevertheless, mesh WiFi network (really independent from providers) is great thing. It's pity, that it never worked on N900, and instead of getting fixed, it got disabled in KP (modules for it cashed crashes, or something like that). Not enough knowledgeable enough people interested in bringing them to workable state, I think.

/Estel