This looks like an awesome project! Another similar one to check out is called Refuge: http://refuge.io/

Wifi mesh networking has definitely been done. Android hasn't officially supported ad-hoc until recently, so it's been difficult (but possible).

There is a project like that, in fact (full disclosure: I am the developer): https://github.com/danstaples/MediaGrid. I bet SplinterNet could integrate well with such a backbone network.