Who else is working on this stuff?

None of the ideas in the ClearSky concept are original to me. This is sort of the zeitgeist of the times. Here's a list of people and projects that have thought about or are working on the same problem:

• FreedomBox Foundation
  
• Dave Taht
  
• Kragen Javier Sitaker
  
• Singly (see also this hype piece)
  
• The guy behind Unqualified Reservations
  
• Tonido
  
• Opera Unite
  
• Vinay Gupta

The basic idea stems back to the home media convergence attempts of the late 90s (and indeed Tonido is still following this marketing strategy).

Why no one has been successful so far is that the solutions offered are too hard to use (if it's any harder than Facebook, very few people will use it), don't address the issue of replication (Tonido and Opera Unite, for example), and don't have sustainable revenue models. I think that with the right design, engineering and business approach, these problems are not insurmountable.

You might notice I left out one project: Diaspora. A look at Diaspora's source code should convince you that while the project claims the same goals, the approach they're taking does not address any of the three aspects mentioned above.