The Open Graph Protocol (via Sam Ruby), initiated by Facebook, looks interesting. A way to automatically position your web page in the social graph is always going to be appealing. Unfortunately, as usual, this will work only with Facebook accounts and the Facebook social graph. I believe that Web is one platform intended to be free of vendors lock-ins, by design. And any scheme that tries to create a lock-in, for a walled garden or not, betrays it at some point. Having said that, it will be interesting to see if it crosses roads with microformats at some point or if other entities start consuming it.