Transhumanism, when boiled down to its essence, is the philosophy and pursuit of becoming more than human. The philosophy extends from the basic observation that humans are conscious of themselves, and are therefore capable of directing their own evolution. Indeed, some adherents go so far as to say that we have the responsibility to do so, since traditional evolutionary selection pressures (environmental factors that cause certain traits to become useful for survival) no longer apply to us. That is, because we do everything in our power to care for the weak, the sick, and the infirm, and because we consider it a basic human right to have children, we are no longer evolving along a positive path. Thus, we must technologically direct our evolution in such a way that the species continues improving.
While that sums up the basic philosophy, there are multiple major factions contained within the overarching philosophy of transhumanism. There are those who believe that a better human can be produced through selective breeding (eugenics) programs, those who believe that biological and genetic engineering is ideal, and those who believe that a better human can best be produced through merging humans and machines. Even within these groups, though, it is rare to find two transhumanists who have precisely the same ideas on how to achieve a better human, or even what qualifies as a better human. Indeed, one of the popular philosophies in transhumanism is that instead of a single species with a single genetic and physical makeup, the species must become a large number of differently-evolved sub-species. In other words, all of the approaches are desirable, since they all (if properly implemented) succeed in humans that are different from the current species. There has always been a strong sense of individuality, and a desire to maintain novelty, among most transhumanists.
A small, but significant, minority in the body modification community sees body modification as the first steps in transhumanism. The connection is easy to see: in casting off the genetically-mandated exterior form of a standard human, we are breaking our minds of the belief that a human must look a certain way. Once the body of a human is modifiable for aesthetic reasons not tied to spirituality or tradition, it is possible to begin to modify that body in hopes of improving it.
Beyond the abstract connection, there are very concrete connections. The aspect of transhumanism generally seen as most immediately viable is the the merging man and machine -- indeed, it is so widely seen as viable, that dozens of major Hollywood films have been made about it, and the word "cyborg" is a household word. The most immediately visible way of merging man and machine is to simply implant useful machines into the human body.
These machines could take forms ranging from so simple an implant as a digital watch to something as complex as a processor implanted in the brain that takes over doing complex mathematical computations. While the watch may seem like a party gimmick, and a brain math co-processor may seem far fetched, they both incorporate into the physical human body abilities that are not present in a standard human.
It is within our technological abilities to design and implant (relatively) complex devices into the human body in such a manner as to expand abilities. However, citing reasons of professional ethics and lack of testing, the traditional Western medical community is generally unwilling to do such procedures, regardless of how minimal the risks may be. Given this, many transhumanists have joined the body modification community to find the surgical knowledge and skills needed to make possible the first experiments in transhumanism.
One such transhumanist is Todd Huffman who in 2004 was augmented with a silicone-coated neodymium magnet implanted in the third finger of his left hand. Huffman's magnetic implant is merely the leading edge of what is destined to be one of the primary aspects of body modification.