If you want to use the Mac OS X Natural Scrolling feature on your Linux machine, then we have just the right application for you. Natural Scrolling is a Linux package that brings you the reverse scrolling feature. Using Natural Scrolling, you can push your fingers upwards to move the page content upwards, and downwards for down scroll, just like one would on an iOS device. This application is available for both Natty and Onerirc, and can be installed from either the source package or by using the PPA given below.
sudo add-apt-repository ppa:zedtux/naturalscrolling
sudo apt-get update
sudo apt-get install naturalscrolling
After Natural Scrolling (app) is installed, you will have to manually launch it from the Ubuntu Dash. Once done, go to the app-indicator and enable natural scrolling option from the application indicator. You can also make the application auto-start with system startup to avoid manually launching the application indicator on a regular basis. While it might be handy for some users to install natural scrolling in Ubuntu, it might not be something that you might not wish to use all the time. For this reason, the natural scrolling feature can be toggled on/off from the app-indicator menu.
While there has been a lot of criticism among Mac OS X users regarding the use of natural scrolling, it will be interesting to see the reaction of Linux users regarding this feature. You can download and compile the source package for other Linux versions from the github link below.