In a blog post from this morning, Cory Doctorow — a technology writer who has given a number of speeches on copyright — explains why ebooks that are available in some countries aren't available in others. Doctorow picks apart the motivations that compel publishers to choose blanket licenses and why they will sometimes opt for granular, region-by-region licensing agreements. If you've ever wanted to get into the finer details of ebook licensing and how international commercial trade agreements work, Doctorow's explanation is top notch.