(defun tell-terminal (commands)
  "Use osascript to tell Terminal.app to do stuff"
  (interactive)
  (shell-command
   (concat
    "osascript"
    (mapconcat
     '(lambda (command) (concat " -e 'tell application \"Terminal\" "
                                command "'"))
     commands ""))))

(defun terminal-there (dir)
  "Open Terminal.app and change working directory."
  (interactive)
  (tell-terminal (list
                  (concat "to do script \"cd " dir "\"")
                   "to activate")))

(defun terminal-here ()
  "Open Terminal.app in `default-directory'."
  (interactive)
  (terminal-there default-directory))

(global-set-key "\C-c\C-t" 'terminal-here)