I think that's what the OP is lamenting: That we've traded one problem (remembering which screen name/e-mail address and password you used to log in) with anoth

I think that's what the OP is lamenting: That we've traded one problem (remembering which screen name/e-mail address and password you used to log in) with another one (remembering which OpenID you used to sign up, and dealing with the technical repercussions therein), while there is a seemingly superior solution out there (let the browser(s) handle it).