will the official book be updated for SilverStripe 3.0? that would be great.
(i am coming from TYPO3 (i am a bit unhappy with the recent updates) and like SilverStripe a lot so far. :) especially i am fond of the MVC-API. what i miss a little is the concept of multiple content elements on a page but i am sure i will find solutions for something similar.)
A book is a significant investment to produce, in the short to medium term you'll probably see more work going into improving doc.silverstripe.org before the book comes out. The 3.0 version will basically be a new book as the platform has evolved significantly since then (composer management of modules, new ORM, new templating implementation, new config api, Dependancy Injection..) lots of great new tech that would need to be covered.