Every monicker used to describe a movement (i.e., conservative, liberal, etc) has undergone numerous redefinitions over the generations, with libertarians undergoing the same reclassification. Many libertarians foolishly claim they adhere to the standards of the Founding Fathers, although it is certainly arguable that they would NOT be considered libertarian by today's standards.
Do you honestly believe that you know what defines a libertarian or are you just saying that you know what defines libertarians at the moment?
Just as their are differences among conservatives, there are clear differences of opinion among those who call themselves "libertarians."
Which one is correct?
From http://www.libertarian.org :
"While libertarians are a diverse group of people with many philosophical starting points, they share a defining belief: that everyone should be free to do as they choose, so long as they don't infringe upon the equal freedom of others.
Human interaction should be peaceful, voluntary, and honest. It is never acceptable to use physical force to achieve your goals. The only time force is acceptable is when you are defending against force."
That's about as good a definition as there is, IMHO. There will always be differences of opinion amongst individuals about the issues of the day, no matter what they choose to label themselves with. The defining principle remains.