I just updated to usermode-1.35-1. Since then, shutdown does not pay any attentin to the "time" specified for shutdown. If I type shutdown -r +15 the system shuts down now. If I give an absolute time, as in shutdown -r 10:00 the system still shuts down now. This has happened on more than one system, and has happened using shutdown -h as well as shutdown -r.
The ability to run shutdown with arbitrary arguments had to be removed. The /usr/bin/shutdown script is provided so that the GNOME logout dialog will still present the options, but any use of -r will run /usr/bin/reboot, and -h triggers /usr/bin/halt.