.emacs.org-insert-heading-categories-all.el

;; http://article.gmane.org/gmane.emacs.orgmode/10256
(defun org-get-heading-title ()
  "Returns the heading of the current entry as a string, without the leading stars, the TODO keyword or the tags."
  (let ((title-with-props (org-get-heading t))
        (keyword (org-get-todo-state)))
    (substring-no-properties title-with-props (if keyword (1+ (length keyword))))))

(defun org-insert-heading-category ()
  "Insert a :CATEGORY: property and it's value to the PROPERTY drawer at point."
  (interactive)
  (let ((point (point)))
    (org-entry-put point "CATEGORY" (org-get-heading-title))))

(defun org-insert-heading-categories-all ()
  "Insert :CATEGORY: properties to each headlines indented level 2."
  (interactive)
  (org-map-entries
   (lambda ()
     (if (eq 2 (org-current-level))
         (org-insert-heading-category)))))