There is a bug in OpenSolaris 2008.11, that make SMF hang for a few minutes before put SMF gdm into the maintance mode when shutdow OpenSolaris.
The fix will be available in the next OpenSolaris Release, but you can simply resolve it now by yourself. (fix is now available in snv 105)
As a root user, make a bakup of gmd script file
# cp -p /usr/sbin/gdm /usr/sbin/gdm-BUG-4887
And then edit /usr/sbin/gdm script file with your best editor (vim) and then remove all the following lines:
# GConf now needs D-Bus, so to launch AT programs it is necessary for D-Bus to
# be started with gdm. We start D-Bus as the "gdm" user. We do not do not
# need root privilege for this since the GUI and AT programs all run as the
# "gdm" user.
#
eval `/usr/bin/su - gdm -c /usr/bin/dbus-launch --sh-syntax --exit-with-session`
export DBUS_SESSION_BUS_ADDRESS
export DBUS_SESSION_BUS_PID
Then restart OpenSolaris