OpenSAML user discussion

Hi,

My company wanted to implement SSO for interanet web application. I had went 
through GSS-API using kerberos API. But the security team told that for 
kerberos authentication firewall port needs to be opened . They suggested for 
SAML. I went through SAML specification. It specifies the message flow but . 
It didn't specify the authentication technical details.Then i searched for 
SAML implementation toolkits and found in sourceid. But they also have 
something called Federated Identity . Now I am confused what to use. If 
possible kindly provide the details as a difference between SAML , Federated 
identity and JAAS using kerberos.

Thanks,

Bala.J