It's a great idea to put your Puppet manifests in a version-control system, such as Git or Subversion (Git is the de facto standard for Puppet). This gives you several advantages:
- You can undo changes and revert to any previous version of your manifest
- You can experiment with new features using a branch
- If several people need to make changes to the manifests, they can make them independently, in their own working copies, and then merge their changes later
- You can use the Git log feature to see what was changed and when (and by whom)
