I've created a script for moving posts to / from subforums. It would be really nice if Nabble would implement this functionality directly so I don't have to keep adjusting it when the URL format or page layout changes.
If you're familiar with the Firefox Greasemonkey script management system, it should be easy for you to adapt this script to your own forum.
To use it, save the file out and rename it to your own name, ending in ".user.js" and edit the main forum page URL and the subforum names and their page names, and then visit the resulting file in Firefox. The Greasemonkey addon (which you have to install itself) will notice and let you manage the page.
http://wa5znu.org/2009/08/nabble-move-starred-topics/Leigh.