My read on that is that the 'feel' of the analog sticks can be affected - perhaps somehow feedback can directed at and through the analog stick, or maybe even there are specific per-stick motors. They talk about 'texture' there in the context of motion, and the Wired article talks about a sensation of walking on ice vs plodding through mud. So I think it is something to do with the analog stick specifically and its relationship with the rumble, and how that can be used to change the feel of motion under control of the stick (rather than the sense of what your other fingers are feeling on the pad).
That and the 'actual' force feedback/programmable resistance in the triggers sound like the two biggest departures from what we've had to date.
