I can see that problem solved or attenuated if those meshes turn into some kind of distributed networks like bitmessage or bittorrent where everyone has duplicate pieces of a larger "file" thus ensuring almost 99% availability. Data put in the network would be everywhere and maybe a distribution algorithm could ensure that there's always a complete source on one node so the swarm could be rebuilt if one node goes down.
Of course the bandwidth will be nothing like what ISP can offer.
What concerns me is how highly vulnerable to RF disruption some of those projects relying on WiFi are. This is a serious problem if you are trying to communicate vital information in a country where the government is hell-bent on not letting citizens set up counter-revolt or grass-root movements because it'll actually be very cheap to disturb those signals (I may be wrong but from what I understand of WiFi freq. range it's easy to neutralize a network by flooding it with interference).
edit:
But maybe we don't need 24/7 availability for those kind of network usage. Well-organized revolutionary and underground movements might not need a youtube or facebook uptime.
