Has anyone extended Umbraco to allow users to be authenticated without having to login?

An example scenario is where the application is sitting within an Intranet so users have already had to login and a global cookie that holds session variables with the users credentials is then available. So to prevent them having to login a second time, I want to authenticate the user just by checking a userid session variable against the username in the Umbraco db. I will have already created the Umbraco user prior to this.

I have seen Ruben's code which works with members (http://ruben.3click.be/blog/integrating-an-existing-authentication-system-with-umbraco) and was wondering if anyone has modified this for users.



Thanks

James