Proudhon and intellectual property

Apparently I missed a post on the C4SIF site last March, claiming that Proudhon was an advocate of intellectual property. Now, as I am a notorious softy on that question (or self-serving reactionary, depending on who you ask), I’m less inclined to “pistols at dawn” than some might be, but it doesn’t sound much like the Proudhon I know. You can check the comments for some discussion with Stephan Kinsella about the question, which is rendered more difficult because the text at issue is from the half-translated and notoriously difficult System of Economic Contradictions.