Not perpetual
The magnetic pull will gradually fail over time thanks to the element halflife and will always vary slightly with the shift in the magnetic pole (of the Earth). Therefore a decrease in the power supplied follows, ergo not a perpetual motion machine. I did a bit of research into this for something else and this tidbit stuck in my head. Slashdot also had a similar story a few months ago but can't be arsed to look through the archives...
(, Thu 10 Jan 2008, 18:04, Reply)