Drupal 6 now includes support for OpenID logins so I've been having a nosy.. My understanding at the moment is that you need to either setup your own OpenID server or use someone elses who is willing to vouch for you. I've signed up with https://www.myopenid.com/ which got me part of the way there. But to stop myself being tied into them I have delegated MyOpenID to vouch for 'garan.org' by adding some header tags into the front page of this site.
More detail here:
and here's a link to the drupal module: