The WebLessons.info site has a new tutorial posted showing you how to use the LinkedIn authentication handling to allow your users to log in with their own account information.

LinkedIn is a business-oriented social networking service. It is mainly used for professional networking. So if you are having an application or website that serves working professionals then its very important for you to implement login with LinkedIn in your application. By this way you can able to access the data of your users like email, work history, education etc. So now let’s dive into the coding part.

They walk you through the various steps, providing screenshots or code where applicable:

• Creating a LinkedIn Application
• Get the API Key and Secret Key
• Create the database and set up the PHP configuration to connect
• finally, the PHP code for the login form and making the request to LinkedIn

A live demo can be found here (but if you're paranoid about your credentials, I wouldn't use it) and you can download all files included in the tutorial.