I have this vague idea of an open, minimal social network that is little more than the internet:

- If you want to just read, use an RSS reader and subscribe to ... stuff.

- If you want to participate, get a personal page via someone like Wordpress that serves RSS, or run your own via your choice of technology if you want.

- If you want to build relationships between RSS serving participants, use the missing RSS feature that allows client RSS readers and site RSS readers (another missing piece) to piece together inter-site RSS conversations and relationships.

- Mix in some personal privacy and control, and you're done.

EDIT: add missing word.