As you’ve probably heard, touchpad scrolling is backwards in OS X Lion. Instead of pulling your fingers down to scroll down a window, you know push your fingers up.
Confused? You will be. It undoes years of muscle memory. So why would Apple do this?
It’s easy: because of iOS. It’s the same gesture you make on the screen of an iOS device when you scroll up and down the screen. You want to scroll down? You pull the content up.
It’s another example of the influence of iOS on OS X.