Back to the subject that started this thread… it appears that a book about Lucasarts is coming!
http://www.cartoonbrew.com/wp-content/uploads/lucas_bolt_b.jpg
So maybe we’ll also see a book about Sierra as well, one day. In fact, from the description in the link, that’s exactly the kind of Sierra book I would have wanted to see: an art-book with early concept-sketches and reference material.