Yes, even ICE4SAFETY has found some usefulness in providing short messages using Twitter.
Feel free to visit http://twitter.com/ice4safety
Just remember in an emergency don't sit around like a mindless automaton waiting for someone to "tweet" you with information ....do something. There are some government sites that would be providing bursts of information assuming systems all worked and weren't overloaded with billions of nonsensical ramblings.
Recall the US Marine Corp. Management Principle - The 70% Solution - In short if you "do something" you have a 70% chance of getting a result versus if you just waited and did nothing.