Sheldon Richman has a nice essay about how the WTO and developed nations are taxing developing nations for the use of ideas. He also provides a nice explanation of the "natural rights" perspective on intellectual property

But how does one own an idea once it leaves the confines of one's mind? At that point, other people have copies in their minds. To interfere with their use of their copies is to violate their freedom. If you've invented and patented the wheelbarrow and I see you using it as I pass your property, no theory of natural justice can insist that I have no right to use my own materials to make a copy of the wheelbarrow. Not only that: no theory of natural justice can insist that I have no right to sell to willing buyers the wheelbarrows I make. But patent law would stop me. Similarly, copyright law prevents me, even in the absence of contract, from nonfraudulently using as I see fit the books and recording media that I purchase.

On the mercantilism front, I will add my own experience. I was at a conference in Barcelona sponsored by the World Bank, and an economist who worked for one of the European intellectual property bureaucracies said intellectual property was good for developing nations - that it would lead to a great increase in innovation in the third world. I objected, and said that while economists disagreed about a lot of things having to do with intellectual property, the one thing we pretty much all agreed on was that forcing IP on developing countries couldn't possibly be good for them - no one who has studied or thought about the matter thinks the incentive effect in encouraging new innovation could possibly be strong enough to offset the enormous cost of having to pay the developed world for all existing ideas. There were quite a few economists at the conference - none objected to my statement.