Google Points At WebFinger. Your Gmail Address Could Soon Be Your ID.

Could potentially make OpenID useful. But I think there's more potential to using a unified ID across the web than just sharing metadata. For example interaction between two services to which you have authenticated.

Well, that's OAuth - which allows you to tell each service that the other can use it.

That's great idea - I've seen Brad talk about this kind of thing back when he was heavily involved in LJ - and I think it has a lot of potential for bridging the gap between email addresses and URLs, thus meaning that anyone at all can cope with OpenID and the like.

And by making it extensible (I love the idea of the "well-known" folder on the protocol page) it can be used for a whole host of future uses. Very nicely done.

EDIT: http://code.google.com/p/webfinger/wiki/WebFingerProtocol is the protocol page.

Didn't Microsoft already try basically this, and fail spectacularly, with Passport?

No. Passport was not federated, open or free in any meaningful sense.

I'm guessing Facebook ain't exactly thrilled by this news.