Check out Diaspora, the Open source social network. It’s just in alpha version right now, but I think it’s got big potential. You can even setup an own Diaspora server if you want.
For the non-nerd user, the gain compared to facebook is that the content belongs to you even after you uploaded it. And you share your content with people YOU choose. This is great for the idea of free information. Thumbs up from me.
If diaspora grows big, I will join. I don’t think I will give up Facebook though. Not in a while. Maybe if diaspora starts using the Facebook API for posting things there 🙂