It should be noted that many PHP applications run inside Apache httpd and therefore can accomplish SSO using mod_auth_saml approach without any programming. Especially useful is mod_auth_saml's ability to "fake" REMOTE_USER subprocess environment variable, effectively enabling any application that supports HTTP basic authentication to also support SAML SSO.
We expect to provide specific integration examples for some software packages. As of 2009 none are available, but Mahara is one of the first ones planned.