This is a very incomplete answer, but one particular idea that struck me about both immediate and long-term communications is the value of a cell phone. A cellular system can become jammed up in the initial phases of any disaster and also get knocked out, but once things have settled down, most newer cell phones give you multiple options to stay in touch--voice, text messaging, email, instant messaging. Granted, all these services go through the wireless provider, but the provider will likely be trying to hard to get things running and stay running, as much as any landline provider. One thing that Katrina taught me was that it can be easy to be displaced from your home or have the home destoryed, so any fixed means of communication, like a landline or postal mail, may be useless so we can take advantage of the roaming capabilities of a cell phone to stay in touch no matter where we end up.

If you can maintain power to your phone, maybe using a car charger or some external power source, like a Charge2Go or Sidewinder, you'll have a means to stay in touch. Probably not 100% reliable, but at least you'll have a chance, even if you're on the move. For those Katrina families that got separated and didn't have any common number to call--I wonder how long it took some families to find each other when the members were moved from shelter to shelter and eventually shipped off to different states?

It's a good thing that people remember, no matter if you have a communications plan or not, that in the first hours or even days of many major events, there will likely be no communications for various reasons, so they should expect that and should not try repeatedly to call into a disaster area.