The other way is to make a copy of your guide at a particular point in time. I wouldn't recommend that this was necessary for all of your guides but if you are doing a lot of work on a guide or have a number of collaborators on a guide or particular project you might want to consider this option.
From the Guides tab on your Dashboard select create a new guide. Select Use an existing guide as a template and select the guide you wish to copy. Give it a meaningful name and keep it unpublished. For example:-
- X_ICAS 30April2012
- Archived ICAS 30April2012
- Copy_ICAS 30April2012
- ICAS_copy 30April2012