The Dock, Launchpad, and Mission Control
OS X Lion includes two features that are designed to work closely together: Mission Control and desktop spaces. Mission Control allows you to see everything you currently have open so you can easily access your open files and apps. Desktop spaces are virtual desktops you can use to organize your open files and apps. Instead of keeping everything open on the same desktop, you can move some of your work to another desktop space to get it out of the way.
Watch the video to learn how to use Mission Control and desktop spaces.