I just upgraded my OpenID with the latest version (the version number isn't explicitly identified, but the download date was 10/4/08).
Detailed diagnostics show everything OK.
After logging in with OpenID, there is no way to get to administrative pages. The blog shows me logged in, but every attempt to visit the "/wp-admin/" page is redirected to the login form. The "user" field in the login form is filled in with my openid identifier.
The redirection URL looks like this:
WHen this used to happen I could type in a specific URL directed to wp-admin and bypass the problem, but not ALL admin URLs redirect to the login page.
This happens regardless of how I use OpenID: it fails in both delegated and undelegated cases.
I have SSL enabled for login but not for administration. I tried clearing cookies for the blog but it made no difference.