I just watched the last two episodes (to date: "Awake" and "Where Bluebirds Fly"). In fact, it was my second watching of "Awake". I hadn't caught it the first time that it was Hook's shadow that came to him when he used the sap from Pan's tree.
Interesting: he was able to separate his shadow from himself, and send the Black Fairy's wand (which we saw previously in "Going Home" --season 3, episode 11) and his hook back to Emma. Then the Shadow talked to her: I wonder what it said.