Inside the Plone Setup you can choose what sort of "Site" 
you would like.
In technical terms we call these "CustomizationPolicies".
By default there are two Customizations:

  * Default Plone - this is the base configuration.

  * Private Plone - this is a customized Default Plone
  which does not allow Anonymous users to view content
  that has not been explicitly made publicly available,
  or "publicized".

    How does this work?  By default Plone uses DCWorkflow
  which allows you to map states to content objects.
  These states have an associated Permission mapping. When
  transitioned this Permission mapping is applied to the
  object.  So the only difference between a publicly
  viewable and private content is its Permission setting. 

    Also it pre-sets the configuration of several Folders
  in the system.  Look at CMFPlone/PrivateSitePolicy.py
  and you can read what the Policy is doing.  Its very
  simple to read and you should get use to reading 
  python source code (its very compact and legible - so
  it doesnt take long to get use to it).  It publicizes
  the Portal object, and publishes the Member folder.
  As well as 'shows' the frontpage (index_html) in 
  the root of your Portal.  Along with setting up a
  new workflow and other configurations.
  
There are other third party policies you can create!
zopezen.org is another policy that you can download
and install.  create a new plone site, select zopezen
and you will have zopezen.org system.

We are looking forward to have more people
contribute CustomizationPolicies to ship with future
Plone releases.  Or to offer the community as third
party add-ons.  


