Excellent post, there are plenty of usability issues with OpenID that still need to be resolved before OpenID can reach mainstream adoption.

OpenID 2.0’s new directed identity feature eliminates the need for users to know their OpenID url, users only need to specify their identity provider. The identity provider returns the user’s identifier in the authentication response. For instance, yahoo users can initiate the sign in process by typing in “yahoo.com” or by clicking on a “Sign in with Yahoo” button.

Simplifying the sign-on experience (redirects, multiple password prompts, confusing user experience) and streamlining the registration process are also crucial to encouraging adoption.