Like on the difference between United State's liberals and european liberals, in this case there's also a general confusion in terms between the US libertarians and the rest of the world ones.
United States' Libertarians seem to stand in the extreme right, claiming for radical diminution of government, to be replaced by free market ruling. Though I fail to see clearly where they draw the line, it seems that any initiative that is not "productive" (as, for example, gubernamental aid to unemployed, homeless or disabled; government-supported school and health care) would not be acceptable. Government would ensure that none attempted against the individual freedom. Their typical vision of this would be infringements of private property rights.
In South America, Libertarians stand on the extreme left, tend to defend variations of socialism and are frequently associated with nationalist movements. Examples: Ejército Zapatista de Liberación Nacional (Zapatist Army for National Liberation), Frente Sandinista para la Liberación Nacional (Sandinist Front for National Liberation), etc.
In Europe, Libertarians are often associated with left-winged anarchism. United States' libertarism, right-winged anarchism, or anarcho-capitalism is virtually unknown, at least to the point where I have notice, and their claims are usually regarded as extreme rightist neo-liberal ones.
Libertarian Communism does exist, as opposed to (for example) U.S. Libertarian Party. One example is Spain's CNT ("Confederación Nacional del Trabajo", National Work Confederation) wich is an anarch-syndicalist trade union. Their flag is diagonally divided in two triangles, the lower black and the upper red, which stand for freedom and solidarity, respecitvely. Although they believe on minimal government (reduced to coordination purposes) for the maximization of individual rights, they also defend the dissapearance of private property, market and money, since they regard them as cohercitive for the people's freedom. (The diagonal divission of the flag also has its meaning, since it calls for the dissappearance of frontiers).
To my knowledge, outside the U.S.A. the Libertarian Community is generally referred to as the people who fight against opression, wether this comes from a market-riden capitalist society, or from a despotic implementation of communism (it is important to note the difference: while most non-U.S. libertarians oppose to capitalism itself, many accept the ideals of communism, if rejecting the authoritaric approaches).
I have no information sofar regarding what does "libertarian" mean by African, Asian or Oceanian standards.
Till here I've stated facts. I'd like now to suplement a consideration of my own:
Etymologically speaking, I think that United States' Libertarians and left-winged anarchists should share the general name of "Anarchists", since anarchism means literally "no government".
"Libertarian", on the other side, stands for liberty and freedom, which are not compatible with capitalist mentality. An exposition of these reasons can be found under the node "Anarchism".
So, essentially, I think that the names are messed all the way around, at least in the United States.