A few years back, there was some discussion on the list about using low-resource systems to provide services in areas with little infrastructure. While this article is mostly about neighborhood wireless-phone access for toll-bypass (beating the phone company), there are plenty of ways that the same technique could be adapted to areas with almost no wired infrastructure to start with.
In short: Linux has been adapted to inexpensive (< $70) Linksys wireless routers to provide VoIP capabilities in a low-power, rugged form factor: http://www.pbs.org/cringely/pulpit/pulpit20040527.html - Bob
