I've been waiting for a book on C from No Starch Press, so I'm really excited for this one.
This might not be too deep a question on the C language in regards to this book, but I've been wondering, why did you decide to have an eldritch horror as the book's cover?
It's a longish story, but people do seem to like the cover. We started equating the idea of C == Sea, so we had some early drawings of the robot riding various undersea creatures including a giant squid. I thought that looked overly phallic, so I suggested the robot ride Cthulhu instead, an unofficial mascot of NCC Group.