Archive DONE items to datetree based on CLOSED time

gistfile1.el

(defadvice org-archive-subtree
  (around org-archive-subtree-to-data-tree activate)
  "org-archive-subtree to date-tree"
  (if (org-entry-is-done-p)
      (let* ((dct (decode-time 
                   (org-time-string-to-time 
                    (cdar (org-entry-properties nil 'special "CLOSED")))))
             (y (nth 5 dct))
             (m (nth 4 dct))
             (d (nth 3 dct))
             (this-buffer (current-buffer))
             (location (org-get-local-archive-location))
             (afile (org-extract-archive-file location))
             (org-archive-location
              (format "%s::%s %04d-%02d-%02d %s" afile 
                      (make-string (org-get-valid-level 0 2) ?*) y m d
                      (format-time-string "%A" (encode-time 0 0 0 d m y)))))
        (message "afile=%s" afile)
        (message "archive-loc=%s" org-archive-location)
        (unless afile
          (error "Invalid `org-archive-location'"))
        (save-excursion
          (switch-to-buffer (find-file-noselect afile))
          (org-datetree-find-year-create y)
          (org-datetree-find-month-create y m)
          (org-datetree-find-day-create y m d)
          (widen)
          (switch-to-buffer this-buffer))
        ad-do-it)
    ad-do-it))

;; Execute the following in the file which you want to archive
(org-map-entries 'org-archive-subtree
                 (mapconcat 
                  '(lambda (x) (format "TODO=\"%s\"" x)) 
                  org-done-keywords "|"))