After allowing you to authenticate your comments using an OpenID, Blogger is now an OpenID provider. To use any of your blogs as an OpenID identity, you need to check "Enable OpenID for blogs" in your Blogger profile (the feature is still experimental, so it's not added in the public release yet) and save the settings.
Blogger inserts this line in the head section of your template:
<link rel="openid.server" href="http://draft.blogger.com/openid-server.g" />
so now you can use any of your blogs as an OpenID. Some simple things you can do with your OpenID are to claim your blog at Technorati (you still need a Technorati account), sign in using your OpenID at Plaxo, Zoomr or post comments in a LiveJournal blog, like Brad Fitzpatrick's blog. A small inconvenience is that Blogger uses the subdomain of your blog instead of your name.
Yesterday, Yahoo announced it will support OpenID 2.0 (Blogger is a provider for OpenID 1.1), so the future is bright for this authentication system.
Matt Haughey retires from Metafilter
3 hours ago