Backdrop Folders is an addition to the Finder. You probably noticed, for a given kind of work, that you had to go to the same places with the Finder, again and again. With Backdrop Folders, you can open "views" of your folders at the desktop level and interact with them. These views remain visible when you reveal the desktop with Exposé, which allows you to pick a file or to do a drag and drop operation in no time, without the hassle of having to switch to the Finder and navigate through your disk hierarchy.
