I wanted to drop a note to mention that my UPEI CS 4th year project class has been utilizing FCKeditor as a code base to develop a specialized TEI editor for Drupal. I'm in the process of developing a module section on Drupal now. I'll post a link to that later.
This module is being developed for http://www.islandlives.ca/ - a project by the Library at UPEI to digitize historical documents, and serve images of these documents side-by-side with filtered TEI text captured by ABBYY. This TEI text will be editable in filtered and source formats.
If any FCKeditor developers and/or users have any interest in utilizing our developments, please check out the drupal module link (to be added shortly), or email me at email@example.com.
A documentation wiki is also being developed and will be hosted on the islandlives itself following final production.
Using FCKeditor as code base for TEI development