So after installing the newly introduced Ubuntu Natty Narwhal... you can easily install Skype by using two methods. By using the Software center or the Terminal. But since it's supported by Ubuntu repositories... just use your Software center, it's more easier.
From the top left corner, on the panel, search for "ubuntu software center". Launch the app. Now within the "software center", search for "Skype" and simply follow the instructions.
|Click on the "Install" button and follow the instructions on the screen...|