The original @bluesky proposal, from Twitter last December, envisions allowing online conversations to span providers. So "from inside Twitter I could follow not only other Twitter accounts, but posts on my boat-owners’ forum." Tim Bray (researcher and noted boat owner) adds the following: "it would be of value to @bluesky to have a global notion of identity that is not tied to any provider." What follows is a relatively complex, but still reasonable, way this could be accomplished essentially involving a federation of identity providers. Though as Kevin Marks comments, "this isn't the simplest thing that could work, as we already have that and it's called URLs." Which is what the original OpenID proposed (and if I may say, my own mIDm also).