While this is not a legal document, NSImage class docs have the following text for some constants:

Images representing standard artwork and icons that you can use in your applications

Drag images you can use in your applications.

Images representing sharing permission icons that you can use in your applications.

http://developer.apple.com/mac/library/documentation/Cocoa/R...

However, NSImageNameComputer, which Rogue Amoeba uses, doesn't have "you can use in your applications":

Images representing Finder items.

Though, it has the following text:

You should use these images to reflect specific elements of the Mac OS X environment. For example, you might use the burnable folder icon if your software allows the user to organize content for burning onto an optical disk. The appearance of images can change between releases. If you use an image for its intended purpose (and not because of how it looks), your code should look correct from release to release.

Does Rogue Amoeba use these images to reflect specific elements of the Mac OS X environment? I guess so.