Each server is single-profile? If so, I agree that that's a terrible design. I'd assumed that it was more jabber-like in that anyone could start a server, rather than having to have one.
Also, TechCrunch did a story on them recently; http://techcrunch.com/2010/05/13/onesocialweb-were-ahead-of-...
If people actually care, there will be a number of services providing "servers" under various conditions. Some will be advertising supported. Some will be for-pay. Some will be subsidized. Some will be shared. Some will be virtual. and so on.
Honestly, I am assuming one goal will be to make it flexible. And a second goal and major dev effort (or maybe even a plea for help) will be to make it so a child can use it effectively.