So the real question is when are ARES/RACES groups going to realize its time to implement this using products like the Ubiquiti NS3/XR3 on 3 GHz, the lower half (2.3 GHz) of the 2.4 GHz ham band, the 5.8 GHz band, or even 900 MHz with something like the XR9.
Ubiquiti's AirOS firmware as well as popular third party firmware such as DD-WRT all now have mesh networking protocols like WDS (Wireless Distribution System) built in.
Mesh protocols are designed for self-healing networks that are able to load balance WAN (wide area network) access. They also combine some of the ideas contained in the Radio Shortest Path First protocol. If the you are not up to par on the dynamics of mesh networks, here are a few links:
http://www.olsr.org/ An ad hoc wireless mesh routing daemon
You may also wish to read the article by John, K8OCL, titled "New High-Speed Multi-Media Radio Mesh Networking," printed in the Fall 2008 CQ-VHF magazine.
Mesh is very powerful stuff. And when you throw SIP / Asterisk based telephony on top of it, you have an instant voice system. Just plug in an IP phone or analog telephone adapter. Now not only can you exchange large image files, email, word-processing and other files that emergency responders and served agencies find invaluable. You can also pick up a phone or (seamlessly) bridge existing ones that are dead due to a land-line failure... etc.
Emergency communications offer the greatest opportunity for Radio Local Area Network (RLAN) technology to excel and for amateurs to push the envelope in the public service sector, using this technology....
Another good read is the Winter 2005 issue of CQ-VHF. John, K8OCL wrote a HSMM column on a HSMM portable setup for EmComm organizations.