That feature is on my Kindle and my laptop app for Kindle, too. It is a cool feature.
My nephew put in a proposal at the high school where he teaches to do a completely wireless social studies class next year. They accepted it and bought new iPads for the students enrolled in the class (have to be returned, of course) and purchased a new iPad for him. The text book and all assignments will be on the iPad. He is really excited about it, and I am anxious to hear how it goes.
He has the e-book app, needless to say, on his iPad, and he loves it. We seem to be moving at the same rate technologically, lol. Guess that makes sense...he is only 8 years younger than me! I think you would get hooked if you were to try it.
I started out with the intention of just keeping my personal reading on my e-reader, but once I discovered how many of my professional references were available, I was off and running! I love the idea of having my professional references in my purse where ever I happen to be, since a lot of my work is in the field. I hate being office bound, and this is a great advantage to me. No more lugging huge book bags around with me. Just a lap top case and a purse now.