As to the Venn diagram that is Mastodon + MetaFilter, we just finally rolled out a Mastodon preferences option for folks to list their accounts here on their MeFi profile pages. Dumb little thing but also nice.
Follow friends and discover new ones. Publish anything you want: links, pictures, text, video. This server is run by the main developers of the Mastodon project. Everyone is welcome as long as you follow our code of conduct!