Xcode 4.4: how to copy on other machine
Xcode, from version 4.3 on, is a single app and self-contained. Source :


  This version of Xcode is distributed as a single application bundle,
  Xcode.app, installed through the Mac App Store directly to the
  Applications folder. Installing Xcode 4.3 no longer requires the
  Install Xcode application


The command line tools, which are stored elsewhere on the filesystem, are an optional download which you can install separately.

When copied over manually, the App Store will recognise Xcode.app's presence  and change the badge for the application in your "Purchases" from "install" to "installed".