Drupal is a content management system (CMS). It seems to be pretty popular in this crowd. It is implemented in PHP. There are many useful plugins for it. Is the present site based on Drupal?
Joomla is another CMS implemented in PHP.
Plone is a CMS implemented in Python.
For someone's listing of CMS implemented in Ruby on Rails, see Top 20 Ruby CMS. A search on Google for mentions of "Ruby" and "CMS" in the same article produced about 2.8 million hits.
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