You'll notice a small pop-up bubble that says, "3 other people highlighted this part of the book." The popular highlights have dotted underlines, setting them off from the rest of the book. In fact, you can see another one at the very top of that same page.
The cool thing about this is I can see what other readers felt were the most interesting aspects of the book. That's nice for a story about the 1960 Pirates but it becomes even more compelling when applied to how-to guides or textbooks.
What if a chemistry e-textbook included highlights from everyone else who used it in previous semesters? That capability exists today and becomes more valuable the more the book is used and highlighted. Take it a step further. What if you add notes to that e-textbook? Again, the more it's used the more valuable it becomes.
One problem here is that each e-reader platform (e.g., iBooks, Kindle, etc.) will implement their own versions of these highlighting and commenting features. So, unfortunately, the comments/highlights added by Kindle readers won't show up when iBooks readers use the same book.
Nevertheless, this could easily grow into a very valuable feature. So valuable, in fact, that I could see a model where it helps distinguish one retailer's version of the book from another: If the iBooks edition has more highlights and comments, it's a more attractive option than the Kindle one with fewer highlights/comments; that leads to more people buying the iBooks edition, adding their own highlights/comments and creating a snowball effect. If ebook retailers are smart, they'll invest heavily in this functionality since it will help distinguish them from their competitors.
Btw, I'm sure somewhere deep in Amazon's end user license agreement (EULA) I allowed them to share my highlights with other readers. OK, but wouldn't it be nice if publishers and authors could turn the tables and say, "sure, you can capture all this information, but when you do so with our products you need to share the results with us." We'd learn more about what readers think of our products, which pieces they felt were most important and if we're smart, we'd use that knowledge to create better products (e.g., revisions, related titles and supporting materials). That's wishful thinking on my part though, I'm afraid. As a publisher, of course, I'd love to see the Amazon's and Apple's of the world simply share this information with their publisher partners, but I figure it's more likely they'll charge for it as they do other services.
Why does this feature have to begin and end with books though? I think it could be even more useful for newspapers and magazines. I can't keep up with all my news sources and I'd find it extremely helpful if I could just quickly glance at the key elements of a story, as highlighted by all those people who read it before me. Sure, the newspaper sites offer commenting functionality today but they don't let readers highlight what they feel is most important. Newspapers feel they're being ripped off by Google and other search engines? They should make this highlighting feature a key element of their e-subscriptions, something that's not accessible through their free website. Wouldn't it be cool if your local e-newspaper subscription showed up on your iPad each day with yellow highlighting of the key pieces of each story? What we're really talking about here is convenience, time-savings and a service that's not accessible through the free access option of a website. I'd pay for that!