Pope writes book on Jesus

 "In "Jesus of Nazareth -- The Infancy Narratives," the pope says the Christian calendar is actually based on a blunder by a sixth century monk, who Benedict says was several years off in his calculation of Jesus' birth date." 

http://wwrn.org/articles/38581/

and here and here

I wonder how it checks out with the other "Historical Jesus" work. And what this means for the Catholic Church's stance on historical Jesus.