The Z online help system provides links to in-depth product guides, programming references and other resources.
General documentation for the use and management of built-in and add-on products, as well as an extensive DTML manual are available on the Zope website at http://www.zope.org.
The Zope Guides are a great place to start learning Zope.
There is currently an online object reference that documents the services provided by high-level objects such as Documents and Folders. Other references will be added soon.
One of the best resources available is the Zope mailing list. You can subscribe to the mailing list by sending an email to zope-request@zope.org and including the word "subscribe" in the subject line.
There is also a Zope documentation project working on a Zope FAQ