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.
I agree that any form of censorship is a slippery slope. But this is simply not possible. For one, under the current corporate domination, what they decide they don't like will lead to you being taken down just the same as anything that is 'illegal'. Secondly, almost no one wants want to participate in a place where people comment "nigger nigger nigger" and "Joooz are evil", so you end up with just that.
Unfortunately, censorship to some extent is necessary for the survival of any community.