The Eiresphere is all over this. TCAL quotes from Techcrunch:

You can currently log in to PeopleAggregator with a LiveJournal or Flickr ID and cross post automatically to LiveJournal, Xanga and any other system that uses the Blogger, Atom or Metaweblogs APIs. Microsoft recently announced the renaming of its new open identity standard, CardSpace, and that will be one of many identity standards supported by PeopleAggregator. Canter expects AOL, Yahoo and Beebo to get on board soon - MySpace will be the hard one, he says.

PeopleAggregator.net. You’ll need an invite, a Flickr or Livejournal ID, or something.