Hoax, misprint or other. The ISBN resolves to a 5D Mark II book by the same author. 5D Mark III and 5D Mark II on Amazon France. The 5D3 book is showing up across lots of book selling sites. Could be a placeholder, could be someone having fun.
Thanks to everyone that wrote in about it.
It has also shown up at Chapters in Canada. (thanks terry)
From Amazon France
A new book dedicated to a 5D Mark III has appeared on the Amazon.fr web site. The release date for the book is March 9, 2012. The book apparently comes from Pearson, which is pretty reputable. The author has done books for the 60D and 7D as well as others. Books appearing on Amazon before a camera announcement does happen from time to time.
5D Mark III/X Announcement date?
The last announcement date I received about the next 5D, was March 2, 2012. That's a Friday, which is unusual, but not unique.
However, there is no date that I am 100% confident of.