See and Feel the iPhone

A recent patent backs up an idea I had about a haptic interface for the iPhone (it's not a new idea even for the iPhone):

The proposed solution is the adoption of "haptic" display technologies which allow for some tactile feedback from touch screen displays. Apple proposes including a grid of piezoelectronic actuators that can be activated on command. By fluctuating the frequency of these actuators, the user will "feel" different surfaces as their finger moves across it.