The Nikon D800 book listing on Amazon now has a release date of May 4th, 2011:
The previous listing was for March 9th, 2011:
Before that, the release date was February 9th, 2011:
From previous email communications, the publishers insisted that this book is real and will be released on the specified date. Obtaining a book ISBN and listing it on Amazon is obviously not a complicated task and book publishers may create several "vaporware" books (there is a service fee associated with all ISBN applications).