gnome-power-manager
how it works?
http://moimoitei.blogspot.com/2007/03/debian-etch-gnome-power-manager.html
http://www.tmtm.org/ja/tdiary/?date=20080218
hal-system-power-suspend-hybrid-linux
and
hal-system-power-suspend-linux
http://ubuntu-virginia.ubuntuforums.org/showthread.php?p=5954522