And therein lies a fundamental difference between many libertarians and conservatives. We libertarians tend to see capitalism as a means to an end, not an end unto itself. Property and happiness which in turn lead to a peaceful society are the end, and if people want to work together for free then that's their perogative as property owners and producers.
Many "anti-Communists" sound like Fascists. Capitalism is about pluralism. It is about being able to form your own economic relationships with others. Libertarian Capitalism and Libertarian Socialism can coexist in the same society. Under a Libertarian (ie culturally Capitalistic) society you can have privately controlled worker communes working together with privately owned companies. I for one am sick of those who see a communist under every rock and tree and want to have the "one pure and true economic relationship" be established as the only legal one.
If you believe in economic freedom, you see no evil in the GPL. No one is forcing you to use it and no one is forcing you to use software written with it. If you are so inclined, you could rewrite any GPL'd library under the BSD license by simply emulating its behavior with new code. There is nothing stopping Microsoft from writing a new GTK-compatable library under their EULAs and using it for Linux apps. Nothing.
Bingo--the problem arises when one is coerced into specific actions by government edict. I have always liked the term "free enterprise" FAR better than "capitalism". The very notion of "capitalism" is VERY overly simplistic (as is Communism, Socialism, etc.).