Show dock in fullscreen apps osx lion

This is a cool trick, I found it by accident.

to show the dock in a full screen app in osx lion

• move your mouse pointer to the place where the dock usually is [like the bottom of the screen, or the left / right of the screen if you usually have it there]
• move your mouse agin, in the same direction, as if you are trying to go off the screen
• the dock appears :D