Comment 12 for bug 951123

"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[s] this feature “natural scrolling”. Not everyone love[s] this feature, but if you are one of those ... to implement this feature in Ubuntu, here’s how you do it:"
http://maketecheasier.com/reverse-mouse-scrolling-direction-in-ubuntu/2011/09/16

It's also called reverse scrolling and Apple did not invent it. They just realized it was a natural progression and a way to consolidate with the touch screen (which is where this stems from).

It's not arcane or weird. I can just imagine that touchscreen users could be affected by this as well, and since that's the new market everyone (including Canonical) is vying for, it's noteworthy.