This is quite neat: based on WiFi Signal Analysis, Basic gestures can be recognized. I can't wait for the next Generation of gaming consoles coming out – could you imagine a Wii without having to hold a band, stick, or other control Device? Or a Kinect that works even from behind a wall? And not even optical recognition needed to Analyse the Situation, meaning potentially closer to real-time reactions and more processing Power available for physics models and other effects.
At the same time, it's also quite invasive. Triangulating signals from a router at a known position in order to analyse movements and guestures on the other side of a wall means that someone parked outside of your home – where WiFi is typically still reachable – could reconstruct exactly what you are doing. Without a video camera. That's a scary thought. But it also opens amazing possibilities if used as input for augmented reality devices, such as on-wall monitors, or perhaps also as an input source for google glass.