/System/Library/CoreServices/Finder.app/Contents/Resources/MyLibraries/myDocuments.cannedSearch
. It is a special type of folder, called a bundle, that has an extension. You can usually access the inner part of these by right-clicking and choosing 'Show Package Contents', but with All My Files you can't due to Finder's special treatment of it.search.savedSearch
which is just a Smart Folder property list. This is a search for all files within your home directory.~/Documents
. The odd thing about this is it only happens for All My Files, and not other Smart Folders, which don't allow you to drag-and-drop files into them.