I've been crossing my fingers, hoping that SixApart would take OpenID to the next level and open up their systems elegantly - or at least assemble the parts and promote the concept - leading the way for the huge number of social software sites out there to open their data up. This intriguing post indicates that the wait may be over:

We think that the best way for you to manage your network is to stop thinking about all of the little pieces and to start focusing on the big picture: you and the people who matter to you. We think relationships mean more than email addresses or which service you're signed on to at the moment. So we've created an experimental demo based upon open technologies OpenID, the Microformats hCard and XFN, and FOAF that allow you to see your entire network of relationships in one place - across services, across platforms, across the entire Web.

Source: We Are Opening the Social Graph

I wired OpenID into my Memecat experiment but delayed the development of "social networking" with the hope that the next iteration of what BlogLog does would emerge. I would have done "friends" myself, but I don't have too many members. There must be a lot of sites out there in this position.

Check out the video demo.