Commentated is a project mainly written in JAVASCRIPT and PHP, it's free.
A mirror of the commentated plugin from the habari-extras SVN repository.
To use this plugin, first activate it. Then, add the following to your theme where you want the comment preview to appear:
1) A container element with the ID of 'comment-preview'. 2) A container for each field with a corresponding class (.namecontainer, .urlcontainer, .comment-contentcontainer) 3) A placeholder for each field with a corresponding class (.nameholder, .urlholder, .comment-contentcontainer)
With these elements in place, the comment preview will be enabled.