I'm probably late to the party in noticing Richard Posner's book on plagiarism that was originally published in 2007, but it was an interesting read. I do have a bone to pick with calling it a "book" or even a "little book" as it's not much longer than a law review article and you can read it in an hour or two, but it was a fun hour or two on my part. Posner doesn't answer many of the questions he raises about the nature of plagiarism, why it is considered a wrong, when it might not be a wrong, what are the appropriate sanctions etc. However, he raises great issues worth musing about, and it's a great survey of the different contexts in which we see conduct that may be described as plagiarism - including academia, judicial opinion writing, commercial fiction, historical literature, and art. While he talks about the significance of digital technology both in enabling plagiarism and in identifying instances of plagiarism, he doesn't come to any meaningful conclusions about whether plagiarism is qualitatively "different" in the digital world. However, he does look at how different economic models of literary production over the years impact on concepts of the wrongfulness of plagiarism over time. So if anyone is interested in thinking about the broad strokes of plagiarsm, the contexts in which it arises and how it differs from copyright infringement and fraud - and sometimes doesn't differ that much in practice - this is an interesting read.