It's possible to use Linkedin as the authentication method for Moodle now
The user clicks the login with linkedin button
A popup opens that redirects to the linkedin page asking for your linkedin username/password and your approval to give moodle access to your profile. If the user was already logged into linkedin in some other browsers window the popup only asks permission to login using linkedin
When the users finishes the linked in auth the Moodle page reloads and redirects the user the a form asking for the users email.
When finished the users is logged into Moodle and profile information is shown in the linkedin block.