GNOME Power Manager is a session daemon that takes care of power
management.

GNOME Power Manager uses information provided by HAL to display icons
and handle system and user actions in a GNOME session. Authorized users
can set policy and change preferences.

GNOME Power Manager acts as a policy agent on top of the Project Utopia
stack, which includes the kernel, hotplug, udev, and HAL. GNOME Power
Manager listens for HAL events and responds with user-configurable
reactions.