Most Linux distros come with multiple workspaces built-in. Why do people need multiple workspaces? To organize your work of course! You may read a book and take notes in one workspace while browsing the web and chatting on another.
Unity has evolved from a nuisance to a really user-friendly and fun-to-use desktop environment. But, problem -> Unity uses a common launcher to all its workspaces: hence it displays the apps opened in all the workspaces. Where’s the organization here? There’s a bug filed in launchpad addressing this issue at length, but the developers doesn’t seem to find it a priority. If you think this is a concern, please answer ‘Yes’ to the question Does this bug affect you?