Social networks have experienced huge growth in recent years, and it has generated demand for common social networking features in many Web applications. In his JavaBoutique.com article, Saurabh Bhatia walks through the first steps in building a social networking application using Ruby on Rails and plugins.
Specifically, he explains how to set up authentication for signup and login using Restful Authentication and how to add Facebook Connect. He writes:
Most people nowadays have a Facebook account and a lot of them want to avoid the effort of signing up for new accounts on alternative networks. Hence, it is a good practice to add Facebook Connect to your social network. It helps in getting Facebook users onto your website.