While it's not a full blown CMS, you might like to look at the collaborative wiki work which is happening (which I am involved with). This has several things in common with your approach: multiple types of data store (MySQL, Postgres, DBD::SQLite), different formatters, etc.

see the following:

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I'm Not Just Another Perl Hacker

In reply to Re: CGI/FTP security question by rinceWind
in thread CGI/FTP security question by dakedesu

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
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