PirateBox is a self-contained mobile collaboration and file sharing device. Inspired by pirate radio and the free culture movment, PirateBox utilizes Free, Libre and Open Source software (FLOSS) to create mobile wireless file sharing networks where users can anonymously share images, video, audio, documents, and other digital content.
Here's Cringely on getting around the no-web issue. The solutions he mentions are mostly ham radio and dial-up.
PC World's take.
I'm thinking a fellow could set up a 4G/WiMax mesh pretty quick to get high bandwidth video out of an area where the phones and internet are cut off. If a Pringles can on a stick will get you WiFi (802.11) reception over a couple miles, I don't doubt a properly constructed WiMax antenna could reach 20 miles or more. It would be cake to set up temporary coverage of a city or rural area using Twitter or Facebook to arrange things, assuming one made the arrangements before the government shut down communications. Such coverage could be small enough to fit in a compact car trunk, and maybe even drive around while working. You could have unattended repeaters stuck on telephone poles, bounce things from one server to another to get around damaged or captured links...
Guerrilla WiMax. That could be a giggle. Floor is open for suggestions.