I think what's happened is that the actual shutdown process is now invoked via consolekit rather than from gdm:
5489 ? S 0:00 /usr/lib/policykit/polkitd
5497 ? S 0:00 /bin/sh /usr/lib/ConsoleKit/scripts/ck-system-restart
5498 ? R 0:00 \_ /bin/sh /sbin/shutdown -r now
I think what's happened is that the actual shutdown process is now invoked via consolekit rather than from gdm:
5489 ? S 0:00 /usr/lib/ policykit/ polkitd ConsoleKit/ scripts/ ck-system- restart
5497 ? S 0:00 /bin/sh /usr/lib/
5498 ? R 0:00 \_ /bin/sh /sbin/shutdown -r now