Only useful if you connect it in a way that makes it replicate.
WiFi Mesh networks are what you're thinking of here, and I've been thinking a LOT about this watching what happened in Egypt with the internet kill switch and reading in the news that the current majority party in the house is introducing a bill to try to get the same kill switch setup here in the USofA.
An ad-hoc wireless network running on cheap/older hardware, with "store and forward" routing sounds a lot like the old BBS platforms I used to frequent, in particular Fidonet is very close to this idea.
The main thing is Replication - like lotus notes used to do. That way you can get data, and replicate it in case your own connectivity is limited or cut off.
Bittorrent is also a very, very nice protocol for replication of data sets.
Okay, I'm pretty much network illiterate. Replicate?
I'm probably wrong but I think the later versions of that Apple base station can automatically hook up with other Apple base stations to expand coverage. With several of those placed around the neighborhood we could cover just about everyone. I picture people accessing the network, seeing the files and downloading them as needed. Uploading info would be a bit trickier as I don't want it to become the neighborhood porn repository.
As for getting the word out, I'm one of the neighborhood captains and part of my responsibilities is making sure everyone in the neighborhood is kept up-to-date on items of importance such as "yard of the month", missing pets, and community block parties. It should be do-able for me to pass out info on a local net and hopefully find other volunteers.
-Blast