You can write iPhone apps with HTML/CSS/JS, and this book teaches how.
There are a lot of downsides to skipping the AppStore, from performance issues (Javascript is a hell of a lot slower than ObjC) to monetisation issues (people are unlikely to enter their credit card numbers into an iPhone web app, because they're not used to it). Still, it can certainly be used for prototyping and/or trying some app ideas out more quickly than the App Store would allow.