We were unable to find a description of this release on the publisher's site; likewise there was no information on Amazon or Barnes & Noble.
On the author's own site, the following notice appears,
It has come to our attention that the publisher of Mark’s book “35 Days to Gettysburg” sold the reprint rights to Gramercy, a division of Random House. Gramercy has reprinted the book under a new title and ISBN: “The Gettysburg Diaries: War Journals of Two American Adversaries.” The reprinted version is being released in February 2008. This is NOT a new book by Mark Nesbitt!