Good question. I have seen http://drupal.org/project/ga_login http://drupal.org/project/ga_login for Drupal, for example. Likewise, here's a write-up about usin

Good question. I have seen http://drupal.org/project/ga_login http://drupal.org/project/ga_login for Drupal, for example. Likewise, here's a write-up about using a YubiKey with Gmail's two-factor authentication: http://static.yubico.com/var/uploads/pdfs/Howto_GmailYubiKey.pdf http://static.yubico.com/var/uploads/pdfs/Howto_GmailYubiKey... I believe Google Authenticator is based on open standards and open source, so people could standardize on it if they wanted too.