How to add OpenID to a php site?

Question

I absolutely love StackOverflow's usage of OpenID for registration. How would I go about adding this to my site? It is PHP based. I went to openid.net and looked at the libraries there, but could find little in the way of documentation or examples.

Answer 1

This tutorial was helpful for a previous project I worked on using PHP and OpenID. It has an example app.

http://devzone.zend.com/article/3581

_{(source: zend.com)}

Answer 2

Documentation and examples.