http://en.wikipedia.org/wiki/Transhumanism
The article, such as it is, provides a useful snapshot of what the "Transhumanism" label encompasses (both in definition and criticism). The wiki format is well suited to this still nascent developing space of goals, values, and beliefs. It makes for light reading.
In the following though, a simpler definition, one I find more useful in terms of agency and personhood.
"Optimization of one's self and environment in accordance with one's goals."
The desire for existential risk reduction and game theory appreciation would tend to lead to constraints on Highlander-like offings, or alternatively, annihilation in the tumult beforehand. Short of utility-driven moral constraints though, physical modelling will delineate our best-approximation of limiting-possibilities.
Optimization
Re: Optimization
Trying to cook the noodles before you put the water in isn't very smart. The spin on that article was heavily on the physical aspects of this "optimization". There is no point in focusing on accelerating the Human lifespan without first accelerating our ability to intelligence and common sense. I see no reason the extend the amount of time idiots have available to further screw up our world. (Do not read "planet") Transhumanism, I believe, encompasses the entire human condition. If applied with the proper plan, it could very well be successful....undesirable and unnecessary aspects of the human condition, such as disability, suffering, disease, aging, and involuntary death.
"First, learn to use this..."
*points at head*
"...then, I'll teach you to use this..."
*points at sword*
A tool is useless without the intelligence and common sense to wield it correctly and to its best result. This includes the human body.
[color=#00FF00][b]"How do you keep the natives off the booze long enough to pass the test?" Asked of a Scottish driving instructor in 1995.[/b][/color]
Re: Optimization
good read 
also, "immanentizing the eschaton"

also, "immanentizing the eschaton"

Re: Optimization
image hosted by tripod
plz lern 2 internet
plz lern 2 internet
Re: Optimization
right click, copy image location, ctrl-t, ctrl-v, enter, F5
Re: Optimization
lern 2 internet is quicker