Eugen Rochko and team are fighting spammers at mastodon.social:

We’re aware of the spam attack hitting mastodon.social right now and our full moderation and DevOps teams are on the case mitigating any way we can (incl. switching to approval-mode registrations)

Haven’t seen this affect Micro.blog yet, but if anyone notices any unwanted @-mentions or other problems, let us know.

Update: Spoke too soon, definitely hitting us too. 🙁