The Economist tackles perpetual motion machines in an article appropriately titled "Perptual Nonesense". It should be noted that inventors have been pursuing this dream since the beginning of our patent system. Here's what one patent attorney thought about it a century ago:
"The solution of perpetual motion apparently still captivates those who believe in the possible successful solving of such a machine, though the vain efforts of centuries have done nothing beyond showing failure and the wanton waste of energy and money from its votaries. That this Will-o-the-Wisp is still being pursued is evidenced by the continuous so-called new discoveries which are launched with great regularity as the "Eureka" of some mechanical mind".
Source: The Inventor's Universal Educator by Fred G. Dieterich, Washington, D.C., 1911.