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.
That subreddit and similar ones have a scary amount of power.
All they do is brand anything they don't like as hate speech and nazism and the useful idiots do the rest.
A lot of posts have 5k votes, their participation is absurdly high.
Remember that statistically speaking, a huge portion of them are wumao