[JonnieCache]

The interesting thing about disapora was that it was meant to be federated, like wave, and email. Plus is not federated at all.

Therefore they are only similar in that they have targeted people's areas of displeasure regarding facebook, and this is hardly remarkable. They were both built specifically to compete with facebook, so this whole discussion is almost tautological.

[dspace]

Right, Circles only solves the sharing problem. Diaspora has a much larger ambition. Federation allows for communication between instances that are owned and operated by different people, but it also preserves your privacy better. Google wants all your data. However, you can install Diaspora on a home computer so absolutely no one gets your data except what you share.