I wanted to read about the subject because i will need to do a project in the near future and have to decide whether or not the app should be
Native apps, built for a specific platform with the platform SDK (which is isn´t totally free).
Mobile Web apps are server-side apps, built with any server-side technology (PHP, Node.js, ASP.NET) that render HTML that has been styled so that it renders well on a device form factor. This solution is a steep harder developpment curve than the previous one.
Thinking of JQuery mobile and other libraries that really embed the app in the browser and taking full advantage of html5 to do stuff such as local storage for off-line usage! And no need to know Java, Objective-C and other SDK language related to native app. THis hybrid apps will be written -almost- once and will work in any device.
The book mentioned also a lightweight web application framework developed for building hybrid applications that can be found in github site.
It even shows you how to publish it in android market, sorry, Google Play! And Amazon app store!
I would definitively recommend it but i would say that this is really a starting point. A lot of code needs to be done and tested for a complete app.