Time machine and AirDisk

How was this not broadcast over the entire Mac-loving portion of the tubes?!

If you want to use Time machine over AirDisk (a USB hard disk connected to an Airport Extreme), type this into a terminal window on your mac:

defaults write com.apple.systempreferences TMShowUnsupportedNetworkVolumes 1

Mischief managed!

thanks to this guy. Credit where it's due, and all that.