Correction: Due to a too small terminal window, "dpkg -l" was cutting of the version numbers. Using "apt-cache show" I missed that it listed multiple sources. So versions above should correctly read:
Kernel: 2.6.24-24.61 (generic - just updated now)
Moreover I just found information at http://svn.pardus.org.tr/browse/2008/desktop/freedesktop/?view=log&root=pardus&pathrev=55478 that there was a typo in ConsoleKit causing the described "IsCallerPrivileged() failed", having been fixed in r51558 at Aug 08, 2008. Is that related? If so, did the fix make it into the packages (so it must be something different we experience here)?