Wi-fi is used to make wireless data transmission through walls and floors (not always with good results).

But now, researchers from University of Utah’s SPAN lab are using them to detect movement.

And since the Wi-fi signal goes through walls, it can be used outside a house to detect movement inside for instance.

Not shure for what this could be used though…
I mean, it would be very useful on hostage situations if only it didn’t need tons of wi-fi devices to work properly… maybe for construction and mapping purposes?

Source: TechEBlog