Comment 15 for bug 89269

acpi-support does support running scripts on lid clode.
It does not notify a "battery critical" event though. Maybe that functionality could be added to acpid and thus to acpi-support? Does it require polling?

GNU/Linux, not just Ubuntu, needs one single framework for powermanagement, be that acpi, or HAL or laptop_mode, or whatever.
One framework with hooks for various programs is the way to go. I think we can agree on that, at least at design level. Do we?

Also a full powermanagement solution requires:
disk standby,
processor frequencies;
panel brightness,
services start/stop,
actions on critical battery level,
different configuration profiles,
etc...
...and we are far away from that:
gnome-power-preferences uses HAL, acpi-support uses acpid, laptop_mode does by itself, as well as other things. It's a real mess.