I can see how this would be a simple hack to implement.
In the templates/default/editpost.tpl, you would add code to display a button only admins and authorized moderators would see that says something such as, "Convert Post To New Topic." This would allow whoever is moderating the posts, to rename the post's title before he separates it from the discussion (IMPORTAINT!)
In the following step, scripts/doedittopics.inc.php would check if the "Convert Post To New Topic" button was pressed. If YES, it modifies the ubbt_POSTS table with the new information (such as this new topic's title and removing the "Re: " from the beginning of this /new topic title/), along with updating the following fields:
POST_PARENT_ID gets changed to 0.
POST_IS_TOPIC gets changed to 1.
TOPIC_ID gets the next available TOPIC_ID index number.
Bonus points, to make things nice and fancy, append this to the end of POST_DEFAULT_BODY
The above post was separated out of a thread at: http://www.yoursite.com/forums/ubbthreads.php/topics/POST_ID