I really appreciate what StatusNet is doing, but I've found that it's just not useful enough to... use. It's Twitter but more free and with far fewer users. That's rather different from Diaspora and Tent.io's visions.
FYI: Today, Tent.is -- the first implementation of Tent.io, a protocol for fully decentralized social networking -- went from 0 users to 2000. In a day.
...And since it's free, I bet it'll grow MUCH faster than App.net which, after TONS of media coverage and endorsements from the likes of not just Scobleizer, but The Washington Post and even fucking CNN(!), got just ~12,000 people to sign up by the deadline.
Specific sites aside, I'm glad that people are actively creating alternatives to the centralized, corporatized, developer-unfriendly services that currently dominate the landscape.
Even if tent.is now has 2000 users (including myself) over 24 hours, it does not mean that it will reach 12,000 people. With this kind of projects, people tend to subscribe, play with it a few minutes and then forget about it.
Adoption for a user is tied with friends' adoption. Most users won't see any interest in switching from Twitter/Facebook to a decentralized network, because they don't understand the importance of privacy and controlling your own data.