This is touche in development at disney research. This interface can detect not just simple finger touch but complex gestures using hands and other parts of the body. It claims to have 99% accuracy in detecting a gesture. It is based on something called "Swept Frequency Capacitive Sensing" (SFCS) technique. The difference of this technique, in simple terms, is that this technique samples a wide range of frequencies related to the gesture than a single frequency which gives a binary result YES/NO. i.e. touched or not touched. In the SFCS technique, they can detech different types of touch. It can tell if it is just touch, pinch, grasp, etc. All difference gestures are demonstrated in the following video along with the freqency graph for each type of touch.
With this SFCS technique, they can detect multiple aspects of the user using the device. It can detect how the user is touching the sensor, how the user is connected to the ground, and some properties of the individual body. One reason why they say that this kind of research was not done before is due to the lack of fast and inexpensive micro processors. This technique is computationally intensive and it has to analyze hundreds of data points.
Source: http://www.slashgear.com/disney-research-works-on-touche-touch-control-using-body-parts-07226425/
http://www.disneyresearch.com/research/projects/hci_touche_drp.htm
