Out of curiosity, were none of the major tech publishers interested in a book on SproutCore?
I hope it goes as smoothly as they hope, farming out the writing tasks in parallel. I've found it tough to work with just one distributed co-author on a tech book, much less 60.
I'm working with the Three20 framework for the iPhone, and it suffers from similar documentation problems, though it's gotten better in the last few months.