Hi Michael & Josh!
This is a great topic and your book is timely. I did not realize this had a name (SPA). I've been dabbling in it for some time, replacing some of our
Java Swing GUIs with browser-based ones and favoring this for new GUI development and playing with node.js server-side.
Being able to do away with FLASH, the powerful 'built-ins', such as WebGL, in HTML5 & modern browsers, will, I believe, make this one of those big game changers that come around only once in a while.
Good luck with your book,
Kevin Ryan