In the book preview, the screen shot shown for the multi-tasker (long press home key) is not the way the phone looks today, therefore their descriptions of functionality is wrong. I assume that they were working with some sort of pre-release or early release phone which is why it's different, but it makes me wonder what else is in there that is 'wrong'.
However, at 4 bucks it kind of doesn't matter if there is the occasional "oops it doesn't work like this any more".
So, why are folks willing to spend $4 for essentially the same information that Sammy gives away for free, but will balk at spending 99 cents for an app in the Play Store?