Starting with 10.7 Lion, Apple switched the scrolling direction. This can cause some confusion with people used to older Mac OS versions, or those coming from a Windows background.
I wanted to see if it were possible to allow people to toggle this without needing to visit System Preferences, so I did some digging. I found a script for trackpads on Super User, but it used GUI scripting. I modified it for both the mouse and trackpad panes, and posted it to GitHub. Although there are two separate scripts, changing the scrolling direction seems to apply to both the mouse and trackpad.
That said, Charles Edge has posted the best way to do this at Krypted: Disable Natural Scrolling With a Script.
Tested with: 10.7, 10.8