Yahoo announced on Thursday the ability (at the end of January) to use Yahoo! user IDs for OpenID logins, so this doesn't go quite so far, as it doesn't allow the use of the much larger pool of Gmail user IDs.
So how do you enable this? You edit your profile from the beta version of Blogger, draft.blogger.com (if you edit from www.blogger.com you won't see the checkbox) and check the box that says "Enable OpenID for blogs" (see below).
Caveats? No support for blogs that aren't hosted on BlogSpot or are on a custom domain. There's a workaround that may work for some (help page). Also,“Yes, Always” to trust an OpenID site forever, you cannot now delete that trust. We will add this feature soon.
Hopefully the fact that Google has opted to support OpenID 1.1 won't be an issue going forward; Yahoo! has opted for OpenID 2.0 support.
Although you can already login to comment at Blogger using OpenID, this still means that at least as far as actual services go, Blogger and Yahoo! are still both providers, not consumers of OpenID. It would really serve to validate OpenID if they would start allow users to login to their services with OpenID.
The one hint that this may happen, at least for Yahoo!, comes from Jeremy Zawodny ("Yahoo!'s MySQL guru") at his blog, which says:
Oh, and before anyone jumps on me about this not being "full" (meaning bi-directional) OpenID support, I'm quite aware of that. Consuming OpenID is a different beast that can't happen overnight. Give it some time. I'm optimistic that we'll get there.The assumption being if Yahoo! is moving in this direction, so will Google, leads one to hope.