Moving regions up and down by lines

[Dave Benjamin <ramen@lackingtalent.com>]

Greetings,

I have these two functions defined, which allow me to move the region up 
and down by one or more lines, displacing the text around it. This works 
pretty well, but after the call to yank, the region is no longer 
selected (I use transient-mark-mode). I've tried calling 
exchange-point-and-mark after the yank, but it has no effect. Does 
anyone know how to accomplish this?

(defun move-region-up (arg)
   (interactive "p")
   (kill-region (region-beginning) (region-end))
   (unwind-protect
       (previous-line arg)
     (yank)))

(defun move-region-down (arg)
   (interactive "p")
   (kill-region (region-beginning) (region-end))
   (unwind-protect
       (next-line arg)
     (yank)))

Thanks,
Dave