I am using the following code from MVC Storefront to test OpenId in MVC. How do I integrate it with my ASP.Net Membership so I can use roles and save a user name for
The open id provider will return data about the user. If you don't request/require specific tokens of information, then all you'll be given is the user's display name and identity URL.
Depending on what open id library you're using, you can request tokens like FirstName LastName, DOB (if you really cared) and if the user provided that information on their chosen identity, then you'd get it returned to you.
You can then use this to create a new user in the membership system. You'll probably have to give them a dummy password to get around the requirements of the Membership API.
To validate a login, provide 1 form that takes username & password and the other that takes an identity URL. After you've validated the user via open id, try to find the user by username (identity url) in the Membership API. If it doesn't exist, create it.