If you have been impressed with JBoss Application Server v7.0 aka "Lightning", then I have a good news for you. You can now enabled SAML based SSO for your web applications using PicketLink.
A cheatsheet : JBoss Application Server v7.0 and SAML SSO.
The one stop cheatsheet page for various versions of JBoss AS is here.
Please do not hesitate to ask questions at the PicketLink user forum.