Related to bug #353665

Like CPU frequency and the like, wireless network interface power controls are a performance/power tradeoff. Unlike for CPU frequency, though, they're not really system-wide, but quite specific to networking.

Currently nothing in GNOME manages wifi power settings. I think NetworkManager should, rather than gnome-power-manager, because there are times that power levels should be adjusted based on events that only NetworkManager really knows about or controls.

For example, to quickly join a network and get a DHCP lease, it's best to turn off interface power management while connecting to a network. This makes joining the network a LOT quicker.

Also, it's possible NM might eventually want to adjust the severity of interface power management when it detects large amounts of network traffic, so wifi power management can be adjusted on demand just like for the ondemand cpufreq scheduler.

So, here's what I'm thinking might be a good idea:

- gnome-power-manager maintains network card power policies and configuration GUI:
  - On AC, optimize wifi for {best performance|lowest power use}
  - On battery, optimize wifi for {best performance|lowest power use}

- NM uses dbus events from gnome-power-manager/hal/whatever to find out about
AC power loss/gain and switch power settings appropriately.

- NM also watches for and acts on resume notification dbus events by turning wifi power up for rapid discovery of local networks, before restoring power to level specified by power policy

- NM does the same when joining a new network