Quinn Norton of Wired News has had the operation and writes in detail about how it felt, what the problems were, and what she was able to do once it was in place. The most amazing part is that months after the magnet implant fragmented and Quinn lost her "sixth sense," it reassembled itself (magnets tend to draw towards one another) and the sense returned.
What if, seconds before your laptop began stalling, you could feel the hard drive spin up under the load? Or you could tell if an electrical cord was live before you touched it? For the few people who have rare earth magnets implanted in their fingers, these are among the reported effects -- a finger that feels electromagnetic fields along with the normal sense of touch...ef="http://feeds.feedburner.com/~a/boingboing/iBag?a=qRyfsn">
According to Huffman, the magnet works by moving very slightly, or with a noticeable oscillation, in response to EM fields. This stimulates the somatosensory receptors in the fingertip, the same nerves that are responsible for perceiving pressure, temperature and pain. Huffman and other recipients found they could locate electric stovetops and motors, and pick out live electrical cables. Appliance cords in the United States give off a 60-Hz field, a sensation with which Huffman has become intimately familiar. "It is a light, rapid buzz," he says.