Using wireless network signals to see through walls

Bruce Schneier linked to this article, the comments are here http://www.schneier.com/blog/archives/2009/10/using_wi-fi_to... .

This is pretty obviously an outgrowth of the old body capacitance sensors used in monitoring secure areas. It would be pretty easy to spoof since it would also detect moving pieces of any conductors or electronic devices. For SAR they would only detect a person (or electronic device) that was moving; if you are pinned down, tough luck.

Honestly, it is not as useful as ultrawideband handheld radar under prototyping. Surrounding antenna array is just too excessive.

Cool technology, thought the editorialization is a little lame. Really? SWAT? Because anything that can track movement will be immediately useful to SWAT? Wouldn't the base-station have to be inside the building? The author could have tried just a little bit harder to envision a use.

It would be awesome if you could use the wifi on the iPhone to do this and sell it as an app. I'm guessing you don't get that low level of control over the iPhone's wifi though?