Everybody loves touchscreens. Having an intuitive, tactile interface has made smartphones the go-to-gadget for staying connected while on the go. The only problem with touchscreens, even the capacitance ones, is that there's relatively little physical feedback. You could set it to vibrate at a touch, but what about for all the slidey action?
Microsoft may just have the solution. They just filed a patent describing how to create textured surfaces for touchscreens using a matrix of shape-memory plastic. Exposing it to a specific wavelength of UV light raises the mimetic polymer, creating textures. Since each cell is the size of a pixel, you can have textured representations of onscreen graphics.
Of course, since it's got a layer of plastic above the actual touchscreen, this technology may not work at all for capacitance screens. In fact, Microsoft explicitly stated that it's meant for their tabletop multitouch display, the Surface, which uses IR tracking.