Just a heads-up that there are currently efforts underway for the (long overdue) redesign of the error page that shows when the servers are down: https://phabricator.wikimedia.org/T76560 https://phabricator.wikimedia.org/M15/23/
Twitter is the recommended medium to update the public on larger outages (as we obviously can't rely on our own sites for communication in that kind of situation), see also https://wikitech.wikimedia.org/wiki/Incident_response#Communicating_with_the... . And the design team is considering to add a direct link to e.g. @wikimedia on the new error page(s), which I think is a great idea.