When you have two sortable lists, there's a 'connectWith' option in the $(this).sortable()-command that lets you drag items from one list to the other. You can also specify callbacks for the removal and receiving of list items via remove:function and receive:function.
Sth like this: $('#list1').sortable({cursor:'move',connectWith:$
('#list'),remove:duplicateItem,receive:integrateItem});
It's actually pretty easy. See: http://docs.jquery.com/UI/Sortable#options
