A Vision-based Input Interface for Mobile Devices with High-Speed Fingertip Tracking has been created and demonstrated by researchers at the University of Tokyo.
A single camera tracks the movement of your fingertip in front of the screen; a high frame rate is required, but the device can also track the orientation of your finger. Shaking your finger at the device is counted as a "click".
Will the multi-touch give way to the finger gesture? Watch this concise explanatory video and judge for yourself.
A loud clatter of gunk music flooded through the Heart of Gold cabin as Zaphod searched the sub-etha radio wave bands for news of himself. The machine was rather difficult to operate. For years radios had been operated by means of pressing buttons and turning dials; then as the technology became more sophisticated the controls were made touch-sensitive--you merely had to brush the panels with your fingers; now all you had to do was wave your hand in the general direction of the components and hope. It saved a lot of muscular expenditure, of course, but meant that you had to sit infuriatingly still if you wanted to keep listening to the same program.
Zaphod waved a hand and the channel switched again.
Update 15-Jul-2016: Here's an earlier reference to the idea of a gesture interface from Samuel R. Delany's Babel-17 (1968):
Rydra shook her head. She passed her hand before the filing crystal. In the concaved screen at the base, words flashed. She stilled her fingers. "Navigator-Two. . . ." She turned her hand. "Navigator-One. . . ." She paused and ran her hand in a different direction.". . . male, male, male, female...
Rydra watched, her hand drifting through centimeters over the crystal's face. The names on the screen flashed back and forth.
Rydra's hand came down on the crystal face, and the name glowed on the screen.
(Read more about the filing crystal)