[Zope-CMF] User Specific Sites?

[Learned]

I'm evaluating ZOPE with CMF as a tool for creating an
extranet site. Based on who is accessing the site, we 
would like to alter the content that is displayed. In
a majority of cases, this will be merely restricting, 
or making available sections of the site. In looking
at the acl_list security options, it looks like I 
could do this on an individual basis. Is there anyway
that I could implement the equivilent of group level
security so I could restrict/allow an entire department
for example?