I believe distributed to be unnecessary. Build almost the same thing facebook is now but be good.

Follow flickr's community guidelines and minimal design. Allow me to have a profile picture, give status updates, message friends, write on walls, create pages, groups, and share photo albums, nothing more nothing less. No games, no apps. Let me export and delete my data and make privacy settings clear and easily adjusted.

Get the right group of people in early and you have yourself a nice little business and an easy way to get lots of press as the facebook alternative. You won't be bigger than facebook but you'll make a smaller group of very passionate people happy and thats a good thing in the long term.

Edit: If you removed the t-shirt business from threadless you have a pretty early idea of what this might look like.