It's been down for a day, and may be down for a few more. Looks like "Just build your own Internet" isn't a viable option for internet communists, everyone must learn of their peaceful ways by force.
Trying to get to Saidit redirects you to Saidit's Subreddit, in a sad state of affairs.
EDIT:It's come back up since then. Updates in the link.
The admins' obsession with codifying the Pyramid of Debate was always going to be their undoing, because it was inevitable that selective rigor would be enforced on dissident ideas.