Cal-ISO, PG&E, etc have said they don't give warnings because they don't have a way of contacting lots of people at the same time.
They could notify radio and TV stations. There's a whole emergency broadcast infrastructure in place... They might not want to though, as it would also be notifying thieves about affected areas.
The net has a system for relaying messages to thousands of systems in a few seconds. People tweaked NNTP to forward messages almost instantly, across multiple links. NNTP is a tried, and well-known protocol. Multicast and other multi-user messaging systems also exist.
I'm going to assume you mean the Internet community specifically. There are lots of other industries, not sure that worrying about this one in particular is any more important than any of the others. Setting up an NNTP hierarchy is not something that most people non-tech industries are going to be paying attention to. Multicasting doesn't work in most regional ISPs, and it would need a new app anyway, which again not many non-tech orgs would know to use. Mailing lists would probably be the most effective, but not sure that spamming all known mailing lists is a good idea when an outage is only goint to affect a specific area, and nobody will maintain yet another subscription on a list that never gets any traffic. Gets back to radio/tv, which probably have the most visibility for the relevant people, and which is also constrained to geographically relevant areas by default. But they don't seem to like giving explicit notice, as I said, perhaps because they fear resulting criminal activity. -- Eric A. Hall http://www.ehsco.com/ Internet Core Protocols http://www.oreilly.com/catalog/coreprot/