The content itself is just an iframe from a Facebook app. It looks like they went to http://developers.facebook.com/ and created an app, then they added that app to their group page. The app would then point to the website that you create and display the contents in an iframe that can be accessed from the group page.

thanks!

try this maybe
http://wordpress.org/extend/plugins/facebook/
http://wp.smashingmagazine.com/2009/09/14/how-to-integrate-facebook-with-wordpress/