We are starting with an easy-to-use hosted service that will launch in a few weeks. We are catering to the development community by offering a simple, standardized API that will be easy to use. Privacy is a first-class feature, and Tent is specifically designed to be usable by high-risk activists[1] and people in countries that block other social networks.
You're right-- Our plan is to get the protocol and reference server functioning for general use. We're mindful of the notes made here: http://liberationtech.tumblr.com/post/13377461578/how-the-ne.... We have some thoughts on adoption tactics and strategy, but the master plan is still under development. All insights are welcome.
Twitter and LinkedIn are successful in distinct niches from Facebook. Companies and privacy-conscious people apart from activists (Germans?) may also be interested in a social network that lets them own their information.
A hosted service, extremely simple APIs and libraries, and some really great end-user clients will go a long way. Make it easy, in other words, and don't make it technical (except for the people who want it to be).