touch /etc/gnome-vfs-2.0/vfolders/test.vfolder-info
the test.vfolder-info contain:

<VFolderInfo>
  <Folder>
    <Name>Test</Name>
    <ParentLink>~/Test</ParentLink>
  </Folder>
</VFolderInfo>

When I open a nautilus folder with test:// in the location bar the content of
that folder will be shown without taking into account the MIME type ad all files
does not shown the relative MIME Icons.
When I open the Test folder using nautilus directly all works well... ($nautilus
Test).