"Baker is an HTML5 ebook format to publish books on the iPad using open web standards." Question: In todays era, do books need to be constrained by the design of print books? Print books are necessarily a linear sequence of words, sentences, paragraphs, chapters, because paper bound books require the linear sequence. Anybody who's used a wiki website knows that a body of knowledge can be presented in a non-linear format. With modern electronic reading devices like kindle, ipad, etc, why not experiment with totally different ways of organizing things you might call a "book"? What toolchain is required to publish a truly modern sort of electronic book?
The existing standard(s) for electronic books are, I believe, PDF or ePub. Both follow the same model with a linear sequence of words. The Baker framework aims to be a stepping stone demonstrating how straight HTML5 could be used "to create books with real typography, real layouts and high-quality design."
The Baker electronic book publishing toolchain is to create one or more HTML5 files, package it using their framework, use the Baker Framework Xcode project to convert it into an iOS application, then upload to Apple's App Store. There might be another step beyond this: Profit. That's up to you.
The CSS in the package is strictly designed for the iPad. a.k.a. "Limit the width to 768px". Sigh. The iPad is great, but it's obviously not going to be the be-all-end-all of this sort of gizmo.
In other words the Baker format isn't the be-all-end-all of the future of electronic books. But it's showing the way to an exciting future.