In Australia 2.4 GHz Wi-Fi has channels 1 through 13.
The Electric Imp appears to be hardcoded for the US Wi-Fi Channels, so in Australia, you must change your base station to use a US Wi-Fi channel.
Keyworks to help other people with this problem:
Commissioning an imp
Cannot commission an Electric Imp on Australian Wi-Fi channels.
Wi-Fi setup can fail in Australia.
Blinkup blinks green showing it accepts the blinkup configuration but never connects to Wi-Fi.