What is charisma and the  aura of leadership?
Like the US Supreme Court justice who said he knew obscenity when he
saw it, we "know" charisma when we see it.

Charisma, as defined by dictionary dot com, is:
A rare personal quality attributed to leaders who arouse fervent
popular devotion and enthusiasm.
Personal magnetism or charm: a television news program famed for the
charisma of its anchors.
***
Sometimes we feel the "presence" of a charismatic person as they enter
a room.  Whether it is "their" energy, or the "collective" energy of 
the crowd/group we do sense something.

People with "charisma" can rise to positions of leadership and
influence in society, whether deserved or not.  Brad Pitt is a notable
example.

What is charisma?
Is charisma derived from nature or nurture or a combination?
Can charisma be acquired like other "people skills" such as manners,
elocution, poise?

These folks think that charisma can be taught:

http://www.core-edge.com/FAQ's.htm

While I'm sure that certain techniques may help to amplify a person's
charisma, you can't make a silk purse out of a sow's ear. I think
charisma is a lot like artistic ability: if you have a certain amount
of it to begin with, you can be taught how to use it. But, as an old
baseball player (Satchel Paige?) is rumored to have said about sports
skills, "What you got, you can polish it up. But if you don't got it
already, you ain't never gonna get it."

Well, phooey. The link above didn't work because it has an apostrophe in it.

Try this one:

http://www.core-edge.com

From the definition:

http://dictionary.reference.com/search?q=charisma

n : a personal attractiveness that enables you to influence others

Another source that looks interesting is this:

http://cbae.nmsu.edu/~dboje/teaching/338/charisma.htm

And much more we could list as well.

To answer your questions we can look at them one by one:
1) What is charisma?
- More or less a human capability that some people have
that allows them to lead a group small or large.
- Can be attributed as a good quality - Most Great leaders possess this ability.
- Some have a dark side - Such as Hitler.

2) Is charisma derived from nature or nurture or a combination?
This discusses the possibility it is the combination of the two:
http://www.accessexcellence.org/21st/SER/BE/whatc.html

3) Can charisma be acquired like other "people skills" such as manners,
elocution, poise?

There seems to be some groups that can do this as stated by Pink.
See Core Edge Website.

Finally other areas can be shown as well:
http://www.leighthompson.com/media/psychology_of_leadership.htm

A book review gets closer to the truth:
http://www.yale.edu/ypq/articles/oct97/oct97f.html
...Yet Hitler drew upon his charismatic appeal and fostered a bond
between himself and his fellow Germans through his adaptation of deep
and diverse sources. For instance, Hitler manipulated four of the most
forceful sources: that of a parent or lover -- the charisma of
nurturance and dependency, that of a demonic figure -- the charisma of
the outrageous, that of a teacher who guides his pupils -- the
charisma of the ideal self, and that of a leader who determines good
and evil -- the charisma of moral certainty (Stated Sources)...

Can this human capability be learned?
Like any skill if someone has the ability that ability has to be honed.
Guided and nurtured. As Hitler's was through the 1920s and 1930s.
(See literature on Hitler's rise to power)

What is important here is what is needed to aquire that skill.
From the literature it would seem to be several things:
1) Ability to read a groups concious
2) Ability to synthesize this into something meaningful
3) Ability to articulate in writing and speeches this synthesis
4) Ability to call people to action based on the synthesis

So you have to be learned in all these areas to acheive the goals
that you want to acheive as a charasmatic leader.

And it is important to note that the defining point of a leader
that is "successful" is one that has the best interest of
the people they are leading. Thus Hitler was charamatic but
not successful as a leader in the long run.

Where as Martin Luther King was not exactly charasmatic as an individual
from my readings of his life, but his speeches much have been
something to listen to since they are still read today in
schools across America. So he must have had an element of 
charisma when he was on the podium.

So it is possible to become a charismatic leader if you 
understand yourself well and have the ability to aquire 
the following:

1) Ability to read a groups concious
Understand what a group is wanting and needing.
What their deep desires are and what they long for. (Post WWI Germany)

2) Ability to synthesize this into something meaningful
The historical study and understanding of events and
psychology of groups to understand their needs in a concise manner.
(Otherwise it will be a rambling noise that noone can understand.)

3) Ability to articulate in writing and speak this synthesis
The ability to conceptually manage ideas and concepts into a 
form of logic that will supply emotional releif to the masses.

4) Ability to call people to action based on the synthesis
The ability to speak or write publically. One of the most
feared abilities is public speaking. But more importantly
is the ability to convey the emotion and pauses that will
allow the audience to "purchase" the reason outlined.

(Which is why after WW II the Marshall plan was so important.
If they were to implement the same WW I plan again that would
punish the German society there would be another Hitler in
20-30 years.)
See the marshall plan here:
http://www.marshallfoundation.org/about_gcm/marshall_plan.htm

Of course it does not take charisma to be a leader.
Good decision making is all it takes to be a leader.
But adding Good Decision making with Charisma or should we say insparation
is something to admire.
From my understanding Churchill was one of them.
http://www.bbc.co.uk/history/war/wwtwo/hitler_churchill_01.shtml

Hope this helps
SimpleMind_GS

grthumongous...

I think you'll find this recent article, from the WhyFiles
website, admirably addresses your question:
http://whyfiles.org/205charisma/index.html

Charisma in my opinion would be defined as ones personality traits,
more specificaly the ones that appeal to people, everyone has
attributes that appeal to others, In either a positive or negative
way.
Most people who display confidence or inteligence will appeal to
people and be said to have charismatic attributes.
Hulk Hogan , a wrestler from the 80's had a huge affect on the crowds
due to his over-whelming charisma.  Mostly due to his ability to
inter-act with the crowd.
http://www.livingwaters.com  <><