I've checked out Diaspora* and it looks pretty good. There's strong support to incorporate a feature whereby users can export their data and close their accounts and then migrate to a new Diaspora* instance. I like the idea of having standardised user profiles and data schema so the users can have control, authority and responsibility for their own data. It'd be nice to have supporting laws so that users can request to have their data deleted or delete it themselves.
In contrast, it took me two days to delete all my Facebook posts . I tried out a couple of techniques and tools to try to automate the process (macro recorder and a script) but the Facebook developers have cleverly put in randomised changes to the dialogues and processes so it was too difficult. This meant a lot of clicking to manually delete all the posts and I bet they're still on Facebook's database.
In the process, I discovered that a lot of my posts' access settings had been changed, I guess from when they've made those arbitrary changes to their privacy policies and users' account settings. Grrrrr...
I've written an article on StatusNet and Diaspora*: http://blog.matbury.com/2012/01/08/safe-social-networking-alternatives/