What does this mean in Finder windows?

[gabester]

freeradical wrote:
[quote=jdc]
I keep apps in mine, just drag and drop. But you can put just about anything you want there -- files, scripts, folders, etc

Hmm, I've never intentionally put something there. That's interesting. Does this work like the old desktop icons where you could drop a file on an icon and an action occurs?
In practice it should; I've had just enough problems trying to do that and ending up putting the item I'm trying to drag and drop onto one of the Finder Window icons ending up as another Finder Window icon that I've generally given up and prefer to put things that important in the Dock where they will also be spatially consistent so I can rely more on muscle memory. (Because Finder Windows are always moving around my screen... The benefit of being in-window is it can be a much shorter drag path.)