[ChuckMcM]

Ok DD-WRT folks, get to it :-) More seriously though, this is a pretty cool thing, using your motion which is blocking wireless signals to detect motion. In hindsight its kind of obvious since people are 'giant waterbags of attenuation' as my RF buddy calls them. This also means you can probably add something of a burglar alarm/motion sensor system to these things, and if you were careful you might be able to see the movement of people inside a house by looking at the WiFi signal leaving the house. Certainly if you're carrying around and active phone/tablet that would be trivial to do from outside (and by trivial I mean you would have lots of signal to work with and the math would be straight-forward, not that it would be simple)

[stephengillie]

We can track people, cool! And probably kids too! What about dogs and cats? Rats, mice, and cockroaches?

What's the range on this technology, and what happens if we move the router around with us? Maybe we take it to a new building and plug it in there? Or maybe we can use the wifi modules on phones to do this also? It sounds like a great scanning device. And how long before we can also see huge chunks of metal or strong magnets with this technology, based on how radio waves interact with them?

[aidenn0]

6cm is the wavelength at 5GHz and most sensing devices have issues with sub-wavelength objects. If you're paranoid you can hang a bunch of strips of aluminum foil that are 3cm long all around your house, which could confuse the sensor. (see http://en.wikipedia.org/wiki/Chaff_(countermeasure))

[theoj]

Work is underway on 60Ghz Wifi, which has wavelengths of only a few millimeters.

http://www.pcworld.com/article/2030041/meet-60ghz-wi-fi-the-...

In a few years we could have tri-band routers covering 2.4Ghz, 5Ghz and 60Ghz. Correlating the info from all these frequencies should provide a much better picture.