|Actually the PHPClasses site already uses its own private OpenID implementation.|
Allowing authentication via OpenID to some well known providers that have return user e-mail address of the OpenID account is on the to do list.
The e-mail address is necessary to verify that there is a real user with his own e-mail address behind the account, so there is always the verification step to prevent that users spam the site in the usual ways.
Still that will probably allow OpenID authentication via Google accounts and probably other well known popular providers.
Thanks for the suggestion.