@indigo It's software you can run anywhere. I can run an instance at home if I want and have that instance Federate with everyone else. Just like email. And bulletin boards that were on Fidonet back in the day.
Like any Open Source project, Mastodon doesn't necessarily market itself well. As for the problem it solves, I think of it this way: I can get the benefits of a small community like we have on 10C and Pnut (people give a crap and generally behave according to mutually agreeable norms) with the benefits of something that can connect more globally, if desired.
Finding those communities is still the perennial challenge, just like it's always been.
// @larand