Things change. The California Independent System Operator, the folks in charge of the electric transimission grid in california, announced today they've established a new notification service. In case the ISO implements rotating outages or electrical emergencies, they will send e-mail to newsrooms.
From the media release, it appears this is only for members of the media.
For the public, the ISO will add outage information during rotating blackouts to their System Status web page http://www.caiso.com/ Local power companies also have evolving notification policies. As the number of rotating blackouts increase this summer, I expect all of them will provide notification. The Internet will be one of the primary methods for transmitting notifications to the media, which will in turn inform the public.