tl;dr – Just check out the tutorial.
I just want to take a second to thank Damien over at Make Tech Easier for providing some awesome instructions on how to get Ubuntu running on a Macbook Air. I recently followed his guide for Ubuntu 12.10 but have also used his Ubuntu 12.04 guide as well. Surprisingly, Ubuntu runs better on my Air than it ever did on my previous Dell or Asus laptops. Even the screen brightness controls work! I highly recommend a Macbook Air to any Ubuntu enthusiast looking for something new.