The April issue of the Communications of the ACM contained an article about hastily formed networks. A hastily formed network is a network formed in response to a disaster or crisis of some kind. For example, the response to Katrina last summer and fall. Some students at SI collected material about the various responses to Katrina.
Today I came across another story related to disaster response. It seems Tom Evslin and Jeff Pulver are trying to convince the FCC to mandate an emergency voice mail system for people affected by a disaster.