To be fair, this book is about libraries that are strictly MVC implemented in JavaScript, and no more. At the time Alex was writing the book, SproutCore 1.4 was the current version, and is obviously a "full-stack" framework, including a UI library.
SproutCore 2.0 alpha was released on May 25th of this year, so Alex didn't have time to cover it. My hope is that a second edition would hopefully at least mention it, now that it is much more competitive with things like Backbone and Knockout, et al. :)
If anyone needed proof that SproutCore has failed to launch, this is it.