Masashi Ishikawa, editor at Mainichi Communications Inc., sent me the following note on a new NXTbook: The book entitled "LEGO MINDSTORMS NXT GRAY BOOK" will publish on the end of this month.
Following is the announcement of that. But I'm sorry that site was written by Japanese only.
And there is the contents of the book.
Chapter1 NXT SOFTWARE
Chapter2 MULTIPLE NXT
Chapter7 TWO-LEGGED (Betarex)
Maybe some of our Japanese-speaking readers might be willing to provide some further information that can be found on the site?