This is pretty nifty, wonder how it plays!
http://cgi.ebay.com/Rare-OBrien-Walking-Stick-Low-D-Tin-Penny-Whistle_W0QQitemZ7368473086QQcategoryZ91502QQrdZ1QQcmdZViewItem
Mack Hoover’s been doing something similar for years as well. It’s a cool design to be sure -
I knew Mack did a ski pole whistle…same concept I suppose
Mack’s done walking stick varieties as well. If you ever have a chance to visit his shop - do it! His stuff will blow your mind. 
Ralph and Walt Sweet make really nice wooden ones too, in flute or fife models based on an actual museum piece. Apparently in the 17th centry or so these were a popular item.