It is useful now. I have 182 pages written, and it is in a pdf format up on my blog. I am not allowed to post a link to my blog however. Google jwcolby and Blogspot and you get right there.
Just know that this is a very complex subject, so the book is not "finished". But it's absolutely ready and useful in its current state. Eventually it will be in a library state, developed into a framework.
I spent probably four years developing the concepts of object wrappers, and then building out classes encapsulating whatever I thought was a good idea. It became the framework behind a call center app I was writing at the time for Disability Insurance Specialists in CT where I lived at the time. That was the early 2000s.