Amazing Magnetic Switch Using Only Permanent Magnets

This is a very amazing and practical application of permanent magnets which I am surprised is not used more widely right now. When two magnets are facing the same direction they both attract steel and other ferro-metals; but when the magnets are facing opposite directions they "close" the magnetic field and are thus attracting themselves strongly at the expense of the ferro-metals; thus forming a magnetic switch! This raises some very interesting possibilities!