It should be interesting to see something like this in action, should Apple ever use it. As you probably know, many touchscreen devices incorporate haptic feedback to add a bit of realism to the feel of typing.
It looks like Apple is trying to patent an idea that gives that sort of feedback to their devices, but localizes the source of the feedback. This means that the vibration would happen based on where your finger is rather than just vibrating the entire device.
Here's a description:
In an embodiment, a haptic feedback system includes a plurality of actuators to provide tactile feedback associated with an input surface. Each actuator is adapted to be activated independently of the other actuators. The system further includes a controller to activate a first actuator of the plurality of actuators to induce a first vibration at a selected input location of the input surface and to activate one or more additional actuators to induce at least a second vibration to localize the first vibration at the selected input location
Now, here's where it gets very interesting, the patent application doesn't show an iOS device. Instead, it's an iMac and its wireless keyboard.
The company may be experimenting with new kinds of screens and keyboards designed to incorporate feedback. How it can be used still isn't totally clear, but it's an interesting patent application.