As of the 2.3 release, publishing of RPM packages for the Shibboleth SP has been moved to the OpenSUSE Build Service. The root of the repository tree can be found at http://download.opensuse.org/repositories/security://shibboleth/ and there are individual "yum" repositories for each supported platform.
You can download packages individually, or you can install a link to it by copying the "security:shibboleth.repo" file from the root of the appropriate repository for your OS to your repository directory, typically /etc/yum.repos.d/