added a very helpful command prelude-swap-meta-and-super bound to C-c w

prelude/prelude-osx.el

@@ -11,4 +11,21 @@
 ;; but they do need Meta and Super
 (setq mac-command-modifier 'super)
 (setq mac-option-modifier 'meta)
+
+(defun prelude-swap-meta-and-super ()
+  "Swap the mapping of meta and super. Very useful for people using their Mac
+with a Windows external keyboard from time to time."
+  (interactive)
+  (if (eq mac-command-modifier 'super)
+      (progn
+        (setq mac-command-modifier 'meta)
+        (setq mac-option-modifier 'super)
+        (message "Command is now bound to META and Option is bound to SUPER."))
+    (progn
+      (setq mac-command-modifier 'super)
+      (setq mac-option-modifier 'meta)
+      (message "Command is now bound to SUPER and Option is bound to META."))))
+
+(define-key prelude-mode-map (kbd "C-c w") 'prelude-swap-meta-and-super)
+
 (provide 'prelude-osx)