Spotted on Yanko Design, a Nokia concept phone by designer Rune Larsen:

“Among the grievous wrongs done by touchscreen technology, the worst is its disregard for tactile feedback. Without the pleasant sensation of a button being pressed, we are woefully incapable of using any gadget without complete visual attention.

This Nokia concept tries to right this wrong by using a small pump to fill a substrate beneath the screen that gives our fingers something to feel and press. Maybe now I can finally type out these posts while driving to work without having to put my coffee in the cup holder.”