erc growl notifications

(defun growl-chat (title message)
  (interactive "sTitle: \nsMessage: ")
  (shell-command-to-string
   (format "/opt/local/bin/growlnotify --appIcon 'Emacs' -t $'%s' -m $'%s'" 
           (replace-regexp-in-string "'" "\\\\'" title)
           (replace-regexp-in-string "'" "\\\\'" message))))

(when (eq system-type 'darwin)
  (add-hook 'erc-text-matched-hook
            (lambda (match-type nickuserhost message)
              (when (and 
                     (boundp 'nick)
                     (not (string= nick "ChanServ"))
                     (not (string= nick "services."))
                     (not (string= nick (erc-current-nick))))
                (cond
                 ((eq match-type 'current-nick)
                  (growl-chat
                   (format "ERC")
                   (format "<%s> %s" nick message)))
                 ((eq match-type 'keyword)
                  (growl-chat 
                   (format "ERC")
                   (format "<%s> %s" nick message))))))))