gistfile1.el

(defun twittering-update-status-with-region (start end)
  "twittering-mode: update status with region"
  (interactive "r")
  (twittering-update-status-if-not-blank (buffer-substring start end)))

(defun my-twittering-update-status ()
  "twittering-mode: my update status"
  (interactive)
  (if mark-active
      (twittering-update-status-with-region (region-beginning) (region-end))
    (twittering-update-status-interactive))
  )

(global-set-key "\C-c\C-t" 'my-twittering-update-status)