While I agree that consistent penetration and reach is best via AM radio overall, the listener count is not what it once was. SMS messages have the bonus of trickling in during very brief periods of cellular connectivity, even when electrical systems and land lines are down due to damage or overloading, and they go to what I would suggest is the single most ubiquitous means of communicating with the folks who are harder to reach - the ones not in crowds or sitting by a TV or radio. Of course, the EAS folks have been working to consolidate broadcast commercial radio, television, SMS, cable, and other methods and the methods should improve with time. I honestly think that twitter for a general EAS carrier medium is adding an unnecessary level of complexity (this is based on my experiences from both sides of the SS7 switches that carry SMS, their overall reliability and general impenetrability of viruses, the Slashdot effect, etc.) to a good idea. However, as a general purpose, user-configurable carrier for the most desired flashes of specific information and emergency sources, this idea has some solid potential.