Update (2020, eleven years later): see "Source code navigation / Locate a file in the Project tool window"
In the Project
tool window, right-click the Project
toolbar and, from the context menu, select Always Select Opened File
.
After that IntelliJ IDEA will track the file that is currently opened in the active editor tab and locate it in the Project
tool window automatically.
Original answer (2009)
That would be : Autoscroll from Source.
Navigate from a file in the Editor that gets the focus, to the corresponding node in the Project Tool Window.
Fried Hoeben comments that
you get there from the config of the project tool window.
It is not present in the general IDE settings (at least in version 12)