Ah I love this. From Superuser.
Another solution which works for me is to use rsync and exclude all files, e.g.
$ rsync -a /path/from/ /path/to/ --include \*/ --exclude \*
specifies that all directories should be copied, and
specifies that all files should be excluded from the copy.
The beauty of this is that the new directory hierarchy has the same attributes, timestamps, permissions, etc as the original.