Many users were confused by Login screens which contained both the traditional username/password login form, and the OpenID URL textbox. Some users thought that they needed to enter a username, password, and an OpenID to sign in. To reduce confusion, we recommend that Relying Parties clearly indicate that users have a choice of logging in using traditional methods, or by using an OpenIDThis seems incompatible with Google's omnibus proposal - which conflates both.
(If I worked at Yahoo! I bet I'd get tired of writing the '!' over and over in every correspondence or document)