I'm new, and evaluating zimbra as a replacement. It my understanding that documents is beta. I have installed the latest rhel5 release and noticed the following:

Create a notebook under one account.
Create a notebook under that notebook
open a new document
attached a pdf to that document and saved.

Now this is the only doc in the notbook under the account. I then:

share the root notebook with another use with view rights.

Log in on another machine as that user and accept the shared notebook.
I open the notebook and see the other notebook, then open that notebook and see two documents from some other location, neither of which is supposed to be there.