Like so many plagiarists before him, Anderson claims his act was unintentional. The Virginia Quarterly Review first reported his copying, and the explanation he gave us is that he and his editors decided to kill Free's footnotes "at the 11th hour;" though much attribution was restored within the body text, Wikipedia sources were not. This was due, according to the statement he sent to VQR, to "my inability to find a good citation format for web sources (I resisted the time stamp proposal)."
The upshot: Print authors like Mike Pollan were cited for "intellectual debts" Anderson owed them, while many of the forward-thinking, freely-contributing writers Anderson champions in the book got no attribution. As it happens, this is violates the copyright license governing Wikipedia.
Anderson told us, "this is my screwup... I feel terrible about it." The lifted work was "mostly historical asides and nothing central to the book." But history is hardly simple to document, and it would seem a book on free products would be significantly diminished without its passages on the famous "free lunch" of the 19th-century saloon, or the origin of the phrase "there's no such thing as a free lunch."
We'll have the original notes that were supposed to accompany the book, which includes all these, online by publication date
Update: Hyperion, Anderson's publisher, has gave a statement to VQR backing his mistake-not-plagiarism spin:
We are completely satisfied with Chris Anderson's response. It was an unfortunate mistake, and we are working with the author to correct these errors both in the electronic edition before it posts, and in all future editions of the book.