Move line/region up and down in emacs

A line can be moved using transpose-lines bound to C-x C-t. I don't know about regions, though.

I found this elisp snippet that does what you want, except you need to change the bindings.

(defun move-text-internal (arg)
   (cond
    ((and mark-active transient-mark-mode)
     (if (> (point) (mark))
            (exchange-point-and-mark))
     (let ((column (current-column))
              (text (delete-and-extract-region (point) (mark))))
       (forward-line arg)
       (move-to-column column t)
       (set-mark (point))
       (insert text)
       (exchange-point-and-mark)
       (setq deactivate-mark nil)))
    (t
     (beginning-of-line)
     (when (or (> arg 0) (not (bobp)))
       (forward-line)
       (when (or (< arg 0) (not (eobp)))
            (transpose-lines arg))
       (forward-line -1)))))

(defun move-text-down (arg)
   "Move region (transient-mark-mode active) or current line
  arg lines down."
   (interactive "*p")
   (move-text-internal arg))

(defun move-text-up (arg)
   "Move region (transient-mark-mode active) or current line
  arg lines up."
   (interactive "*p")
   (move-text-internal (- arg)))

(global-set-key [\M-\S-up] 'move-text-up)
(global-set-key [\M-\S-down] 'move-text-down)

Update: Install the move-text package from Marmalade or MELPA to get the following code.

Here's what I use, which works on both regions and individual lines:

(defun move-text-internal (arg)
  (cond
   ((and mark-active transient-mark-mode)
    (if (> (point) (mark))
        (exchange-point-and-mark))
    (let ((column (current-column))
          (text (delete-and-extract-region (point) (mark))))
      (forward-line arg)
      (move-to-column column t)
      (set-mark (point))
      (insert text)
      (exchange-point-and-mark)
      (setq deactivate-mark nil)))
   (t
    (let ((column (current-column)))
      (beginning-of-line)
      (when (or (> arg 0) (not (bobp)))
        (forward-line)
        (when (or (< arg 0) (not (eobp)))
          (transpose-lines arg)
          (when (and (eval-when-compile
                       '(and (>= emacs-major-version 24)
                             (>= emacs-minor-version 3)))
                     (< arg 0))
            (forward-line -1)))
        (forward-line -1))
      (move-to-column column t)))))

(defun move-text-down (arg)
  "Move region (transient-mark-mode active) or current line
  arg lines down."
  (interactive "*p")
  (move-text-internal arg))

(defun move-text-up (arg)
  "Move region (transient-mark-mode active) or current line
  arg lines up."
  (interactive "*p")
  (move-text-internal (- arg)))


(global-set-key [M-S-up] 'move-text-up)
(global-set-key [M-S-down] 'move-text-down)