I signed up yesterday. Looks like Twitter but is decentralized like Email. There are already a lot of people there (~56k [1]), Brendan Eich for example [2] and it seems to grow fast.
Hope this works out. Would be a great way to move away from the social platform silos Tim Berners-Lee mentioned.[3]
[1]https://files.mastodon.social/media_attachments/files/000/16... [2]https://mastodon.social/@BrendanEich [3]https://www.technologyreview.com/s/604052/webs-inventor-tim-...