Many users seem to be confused by a "?" icon, and the unavailability of the app when they try to use it. Just like ANY application which you want to keep available, be sure you copy this locally (to /Applications, or perhaps /Applications/Utilities), THEN drag from there to your Finder toolbar.

I'm very impressed that the author has kept this simple, but incredibly-useful script updated as Apple has tweaked the default toolbar design from Tiger, to Leopard, and now Snow Leopard. An excellent utility, which fulfills a definite need for many users, and does so with style. Kudos to the developer…