When Apple releases Mac OSX Lion, one of the changes is the switching of the trackpad/mouse scrolling direction. Instead of scrolling the mouse wheel down to move down the page, you have to scroll up to move down. Apple imported this feature from iOS and call this feature “natural scrolling”. Not everyone love this feature, but if you are one of those who love it, and wish to implement this feature in Ubuntu, here’s how you do it
via How to Reverse The Mouse Scrolling Direction in Ubuntu (aka Natural Scrolling).