First, I totally agree that every socnets has to be able to talk between them. I said that a long time ago.
Second, I'm not sure that tent is the perfect answer to that. Tent is something completely new. And as every thing completely new, it is too young to do anything. It will be a lot of secure problems, things we didn't think about...
So, why don't we use something which already exist ? Look at the movim project. They build it on the XMPP protocol, already used by a lot of projects (Google and Facebook for chat, but jappix, movim, etc...). We should talk to movim developers.
Third, warning, this is a totally crazy idea : why are we using http ? We already have something really awesome and underestimated : SMTP. Think about it. E-mails are completely decentralized. And the protocol is really old, really mature. It is easy to put security on it with S-Mime or PGP. And... everyone already has an e-mail address. And with Mozilla Persona, log in is really easy.
So, why don't we built something on an e-mail server ? Just an interface. Kind of webmail. Just a different way to display e-mails. Think about it. Private message ? A simple mail. Message to an aspect ? Everyone of the aspect is in "cc". Want to mention someone on the message ? He is in "to". Want to share images, or anything else ? In attachment. Reshare ? This is forward. Your stream is your reception folder, your profile, the send folder.
Everything already exists. Everything works well. You can talk to everyone in the world, everyone has an email. And if he doesn't use the social interface, he can read the e-mail correctly, he just doesn't have a beautiful display. You can talk to EVERYONE.
It would be easy to install, too. Because it is only an interface.
The only problem I see is that e-mails send cannot be edited or deleted, so, this can not be implemented in the "network", but if the users understand that this is just a better way to display e-mails, they will understand that they can't delete them after sending.