Power Saving Options on the WiFi Shield

I plan to run my project off of batteries and have been doing research on the power saving options on the Arduino Uno itself (sleep functions, etc.). But the shield seems to continue to run at full power regardless of the state of the Arduino. So I am feeling like all of my power saving ideas are useless if the WiFi shield is going to suck up all my battery anyway. I don't see any libraries that deal with the power state of the WiFi Shield.

Does anyone have any ideas about how to improve battery life while using the WiFi shield?

Do you have to use WiFi?

Why not use ZigBee and a bridge, or BlueTooth, or 433MHz or Optical...

I want this device to connect directly to our network. None of those others can do that without an intermediary. The intermediary is a deal breaker for what we are trying to do.

Then you'll need to control the WiFi's power supply. A P-channel FET or relay might work. Of course it can't transmit or receive when off.

Considering the shield is directly attached to the Arduino, I assume powering it manually is impossible without removing it and manually wiring the shield to the Arduino board. This is not ideal as it adds to the bulk/mess of the unit (part of the reason we opted for the shield to begin with). Although we have not ruled out this approach, it is not preferred.

So it would appear that there are not any obscure power saving features built into the WiFi shield itself (akin to those built into the arduino).

I did have the thought that if I just disconnected the wifi from its access point, right before the Arduino was put to sleep, it might reduce power. I would assume that while the shield is unconnected, it is sitting idle and the radio/device would consume far less power. But would it be enough? Has anyone tested the power consumption of the WiFi shield while in various states?