I still had problems with the Wifi hotkey: the ath0 interface was still up and consuming power. I finally set it up this way:
In /etc/acpi/events/eee-wifi-off and /etc/acpi/events/eee-wifi-on, use the wireless.sh script provided with ubuntu:
Then edit /etc/acpi/wireless.sh and add these lines before the call to toggleAllWirelessStates:
if [[ -d /sys/class/net/ath0 ]]; then
After a reboot, I could totally disable the wifi interface: it isn't returned by ifconfig ath0 and the wifi led is out. I haven't had the time to check battery life without wifi, but it should help.
Now I still have to look at the configuration to get a notification when battery capacity is getting low....