Background here.
UPDATE: And here's another interesting post from Jenkins to which I meant to link: CANONS OF SCRIPTURE. Excerpt:
If you want to understand the history of Christian thought, in the sense of what a substantial majority of Christians actually thought and believed through much of the history of the faith, then you cannot ignore these many alternative scriptures, texts like the Gospel of Nicodemus and pseudo-Matthew, the infancy gospels and the Book of Enoch. They really were that influential. Nor was their impact confined to the poor and uneducated.Indeed.