drupal 7 workbench: Can I limit different users/roles within a particular section via taxonomy?
You use the submodule of Workbench, called Workbench Access to limit users to a "sub section" of the content based on Taxonomy or Menu path.


  Workbench Access creates editorial access controls based on
  hierarchies. It is an extensible system that supports structures
  created by other Drupal modules.
  
  When creating and editing content, users will be asked to place the
  content in an editorial section. Other users within that section or
  its parents will be able to edit the content. A user may be granted
  editorial rights to a section specific to his account or by his
  assigned role on the site.


There is a great documentation page and associated web video for Workbench Access on configuration within the project page.