You might have seen non-touchscreen phones , normal touchscreen phones and phones with support multi touch like the iPhone or HTC Hero. Nokia seems to be working 3D Multi-Touch according to a recent patent filing
The screen will not only detect your finger position but also how much pressure you are putting on the screen. Imagine pressing the screen really hard to delete a message and a soft press for a scroll.
For now its just work in progress and actual implementation might take a lot of time.