Challenge Accepted has been doing really well in its early release on amazon.com. It is the #2 book in Finland, and is the #5 book in Michigan. A huge "thank you" in English and "kiitos paljon" in Finnish to those who have bought the book.
Though the official release date is May 1, the International Labor Day, the book has been out for about two weeks now. Links to ordering information at amazon.com and Michigan State University Press are on the left-hand column of this blog.