Last week, Joanna wrote about giving up on the iBooks app. It generated quite a number of comments, but one in particular, from reader Michael W. Perry, caught my eye. He said: "One final note. You’re starting to discover an issue that ebook retailers have been averting their eyes from. In the near future, ebook buyers are going to become upset when they realize that ebooks have a major headache, they’re scattered across two or more apps and most people have trouble remembering which book is where. Settling on one app is a poor answer. That app may not have the features...