According to source and LICENSE, CAS is licensed under ASL 2.0
According to https://wiki.jasig.org/display/CASC/phpCAS+license phpCAS is licensed under the New BSD License
I think, this is a documentation/wiki issue which could be easily fixed.
Please also note that, according to http://www.apache.org/licenses/GPL-compatibility.html this library could not be used by GPLv2 project.
Thanks for the info. Fixed to reference the License file directly at github. No need to duplicate info in the wiki.