Rocklobster, I have just done a test of this very scenario. If your ipad is signed into icloud, and pages (numbers, keynote, etc) is also set to use icloud, then... signing out of icloud (the option is called "delete icloud account") will disappear all of your iwork documents without warning/asking.
The hope being that if icloud was enabled and working properly, all of those documents will be saved and accessible on icloud.com. (In my work supporting ~2000 ipads I can not put 100% faith in this.)
There is a way to sign out of icloud and keep the iwork documents locally on the ipad; however it requires you take action BEFORE deleting the icloud account. First go the settings pane for each iwork app (pages, numbers, keynote) and turn the "use icloud" slider to OFF. Then open the respective apps and verify the documents are there. Now if you delete the icloud account, you will be prompted - asking if you want to keep the files or delete them. Why, oh, why?! does it skip this prompt in the other scenario?