Just been alerted via UKL's blog to HarperCollins' new policy that ebooks they sell to public libraries will "expire" after they have been loaned 26 times, and the library will just have to buy another copy. (Ms Le Guin, as you may imagine, is agin it.) But why stop there? Why not implant an incendiary device in physical books that will ignite once the last page has been exposed to daylight 26 times? The technology must be there.