If you're looking for a #mastodon instance to join, we've been testing and tuning https://kosmos.social for a while now. Signups are open.

https://instances.mastodon.xyz/ is now tracking more than 300 Mastodon instances. And that's not counting any other gnusocial/ostatus servers. \o/

The #mastodon fediverse is growing steadily, by about 500 users per hour: https://social.lou.lt/@mastodonusercount

The big difference between Mastodon and Identica is that it's accessible to devs. Git/GitHub vs. some Darcs repo + popular software stack.