I notice that that implementation uses the older SHBrowseForFolder interface instead of the more modern IFileDialog interface used by the rest of the file/open dialogs. Any reason not to use this?
For now, I have modified the TOpenDialog interface to accept an option that eventually invokes the Vista dialog with FOS_PICKFOLDERS, and it seems to work fine, so I would think it is pretty easy to add this support in the TWin32WSelectDirectoryDialog methods since it already exists in TWin32WSOpenDialog.