This service will, at least initially, require you to set up your own instance of the software on a server somewhere. If the service catches on, services will arrive that enable users to simply sign up on the Web and start participating, just like they can get an email account through one of any number of free email providers.
Tent is not a bad idea. It’s a great idea. For now, only technology inclined individuals will have Tent, similarly how only technology inclined individuals with $50 will have App.net. But I think this way is better.
Look at WordPress for the example of Tent working and succeeding.