(global-set-key "\C-xt" 'perltidy-region)
(defun perltidy-region ()
  "Run perltidy on the current region or the whole buffer."
  (interactive)
  (save-excursion
    (let ((beg (if mark-active (point) (point-min)))
          (end (if mark-active (mark) (point-max)))) 
      (shell-command-on-region beg end "perltidy -q" nil t))))