There is a PHP sample available on github, but I still have not been able to figure out how to get the SimpleSAMLPHP setup working. Here is a link to the sample on github: phpaggcat.
If anyone has more luck with the github sample using SimpleSAMLPHP and can generate a more complete answer, I would appreciate any tips on making it work.
Edit 08/04/2013
I looked at this again recently and got it working. See my answer here.