Karim Yaghmour is publishing another book through O-Reilly Media called Embedded Android. There is an early release out that you can get here:
I've skimmed through half the book and really like what I see so far. Given that Mr. Yaghmour is presenting at the Android Builders Summit on Headless Android, he is obviously very tuned in to the topic of this blog. I'll be buying a copy as soon as it's available in print format (or for the eReader of my choice).