Talking to a friend, I realised that there are two schools of thought on scrolling. You might be wondering what this might be about. Ok let me put this in context. Think of a touch screen device and a touchpad/mouse.
when you have a long list of items on the screen which overflow, the instinct is to flick the contents of the screen up, thereby revealing the contents below. This is instinctive. to see the word at the bottom of the page, you move the page up.
with a touchpad on laptops and scroll wheels on mice, the scroll is implemented differently. In contrast with the touchscreen, the wheel have to be rotated downwards and with the touchpad, the finger needs to be swiped downwards to reveal contents of the page below.
I know this isn't a fair comparison however, the second case was implemented on a touchscreen device. My Samsung i8910 HD has S60 OS loaded on it. Recently I dug it up from my pile of gadgets as my current handset was dying. When navigating the menus I realised that I had to swipe my finger downwards to move the page up and thus see the items below. The way this worked was by having a implementation of a touchpad on a touch screen device. I feel this isn't good design.
Different devices have different relationship with the content displayed. This needs to be taken into consideration as one of the most important things when designing software for the specific hardware. User experience is at its optimal when all actions are intuitive. Thus if you, the designer, have to think hard about how a user would interact with a system, then its not the simplest design or the most intuitive. However, if you are able to design an interface which doesn't require complex thought and the experience is straight-forward then Occam's Razor applies and you have an optimal solution.