The following code will also cause emacs to auto-perltidy anything you use cperl-mode with.

(add-to-list 'cperl-mode-hook
             (lambda ()
               (substitute-key-definition
                'save-buffer
                'cperl-save-buffer
                cperl-mode-map
                global-map)))
(defvar cperl-auto-tidy t)
(defun cperl-save-buffer (&optional args)
  "Perltidy and save current buffer in visited file if modified."
  (interactive)
  (if (and (buffer-modified-p)
           cperl-auto-tidy)
      (perltidy-buffer))
  (save-buffer))
(defun perl-buffer () (interactive (shell-command-on-region  (point-mi
+n) (point-max) "perl" nil nil nil)))

(defun cperl-auto-tidy (&optional arg)
  "Automatically perltidy (or not)"
  (setq cperl-auto-tidy (if arg t nil)))
(defun cperl-toggle-auto-tidy ()
  (interactive)
  (setq cperl-auto-tidy (not cperl-auto-tidy)))
(defun perltidy-buffer ()
  "Runs an entire buffer through perltidy."
  (interactive)
  (let ((orig-point (point)))
    (shell-command-on-region
     (point-min) (point-max)
     "perltidy -st -se -q -syn" nil t shell-command-default-error-buff
+er)
    (goto-char (if (<= orig-point (point-max))
                   orig-point
                 (point-max)))))
[download]

... and the following will cause vim to autoformat the current buffer with perltidy when you hit F4.
To be put in your .vimrc

map <F4> !perltidy -q<CR>
[download]

++. If perltidy could replace cperl's indentation that would be great. I would assume it could work on small sections of code whenever a block/construct was closed (e.g. insertion of a close brace/paren or semicolon). At my elisp skill level I'm afraid I'd have to resort to something blunt like processing the whole buffer on each character insertion. Now where did I leave my supercomputer? :-)

I don't generally like things that re-indent when I'm not doing something like saving the buffer (obviously) or hitting tab to request a reindent.