A touchable holography display prototype has been built by University of Tokyo researchers. The device adds tactile feedback to a hovering three-dimensional image.
The tactile sensation is provided using an airborne ultrasound wave - acoustic radiation pressure. In laymen's terms, it pushes against your hand. Hand position is determined using the Wiimote tracking system; a retroreflective marker is attached to the tip of the user's right middle finger.
Take a look at the touchable holographic display video below.
(Touchable holographic display video)
In another example, raindrops appear to splatter on the user's hand. The position of the falling "drop" is synchronized with an ultrasound push that you feel on the palm of your hand.
This seems pretty close to the tactile net used by Frederik Pohl's Joymaker, a kind of super pda/phone that he describes in detail in his 1965 novel The Age of the Pussyfoot. The tactile net is used to present the user with a "virtual kiss" from a caller who left a message.
"Man Forrester, the personal callers are as follows:
...Adne Bensen: female, Universalist, Arcadian-Trimmer, twenty-three declared, five feet seven inches, experiencer-homeswoman, no business stated. Her kiss follows."
Forrester did not know what to expect but was pleasantly ready for anything.
What he got was indeed a kiss. It was disconcerting. No kissing lips were visible. There was a hint of perfumed breath, then a pressure on the lips - warm and soft, moist and sweet.