NUI (Natural User Interface) is considered to be very trendy these days although the concepts were around for a long while…
According to Wikipedia, "Natural user interface, or NUI, is the common parlance used by designers and developers of computer interfaces to refer to a user interface that is effectively invisible, or becomes invisible with successive learned interactions, to its users. The word natural is used because most computer interfaces use artificial control devices whose operation has to be learned. A NUI relies on a user being able to carry out relatively natural motions, movements or gestures that they quickly discover control the computer application or manipulate the on-screen content. The most descriptive identifier of a NUI is the lack of a physical keyboard and/or mouse."
You can read more about it in here (but then you will be a geek…).
In mobility, a lot of the NUI concepts are already implemented, with multi-touch, screen gestures, etc. but as time goes by, more of those concepts will be added to our daily gadgets.
Here's a cool video demonstrating a specific implementation of the NUI concepts: