Moodle 2.0 has been out now since November 25th 2010, yes its been a year already!
So here is the list of books, and a short comment about each with some links to reviews.
Moodle 2.0 for Business Beginner's Guide by Jason Cole, Jeanne Cole, and Gavin Henrick (me)
"It’s refreshingly different from the other Moodle books in that its focus is not on students in an educational institution