How about cloud9 (http://www.cloud9ide.com), Bespin (https://bespin.mozillalabs.com/), Codemirror (http://codemirror.net/) or Ymacs (http://www.ymacs.org/).

It would be just lame to have another editor on just OSX only, considering that most people have used some script-able code editor (like emacs or vim) that are openly script-able (or compilable). If it is just for OSX, then there is a specific scripting language called AppleScript which is OSX only and should be even more integrated to the OSX APIs.

Well at least the "Chromium-like" part triggers my thoughts on web based editor.