A progress indicator for code blocks in org-mode

A progress indicator for code blocks in org-mode courtesy
of John Kitchin:

;; give us some hint we are running
(defadvice org-babel-execute-src-block (around progress nil activate)
  (set-face-attribute
   'org-block-background nil :background "LightSteelBlue")
  (message "Running your code block")
  ad-do-it
  (set-face-attribute 'org-block-background nil :background "gray")
  (message "Done with code block"))