Correction: RPIN uses email to reach your PC, PDA, mobile, etc. I happen to receive my messages on my mobile as SMS.

Here in the Seattle area, we have the Regional Public Information Network (RPIN) for which you can register and receive emergency SMS or MMS messages. I signed up a year or so ago and it's been fairly effective. Sometimes, though, there are too many messages that are only relevant to a small population. I live in Seattle and have set my preferences that way, but still get messages about each local county's status. During a big storm, that's a lot of messages.

Great idea, but needs more refinement, as I'm sure will come with more experience.

I've definitely noticed this on the road. You'll be driving along and suddenly there's some goofball mucking up the flow while yakking.