Hi,
Strangely I'm now having exactly the same problem all of a sudden. I've been building the book for about a month now (I've made about 6 before without any trouble) and along the way have been producing a pdf of the book to see how it will look. Yesterday I noticed some of the images seemed to have lost colour when looking at the pdf version and then today, many pictures all of a sudden look exactly like the example you've supplied above.
I've tried shutting down my imac and restarting thinking it was a memory issue, have checked if I had any filters activated (which I don't and I haven't used filters in books before either), have tried repairing then rebuilding aperture, copying the book to a new library, new location, opening on a different mac and then printing again but none of this had any positive effect.
So from what I understand from your last post, the workaround you came up with was to revert to the original of each image that had the problem and then make the adjustments again?