In previous versions of OS X, I could drag an application or any file onto the Finder toolbar, creating a persistent shortcut that works in all Finder windows. It's no longer working in Mavericks.
cmd + drag does the job! This got me trying for a while.
The reverse of this operation is holding command, then dragging the folder back out. The problem of having unwanted folder or files linked and residing on the toolbar confounded me for a long time. It had had the effect of making the Spotlight window INVISIBLE when in Finder.
I was looking for the same thing. The closest solution I could find was to add the app to the sidebar. Select your app and hit Cmd+Ctrl+T.
In OS X 10.9, Mavericks, you have to hold the Option and Command keys to add it.