$ dbus-send --system --dest=org.freedesktop.Hal --type=method_call \ --print-reply /org/freedesktop/Hal/devices/computer \ org.freedesktop.Hal.Device.SystemPowerManagement.Suspend int32:0
http://linux-tipps.blogspot.com/2008/08/standbysuspend-to-ram-with-dbus-in-kde.html