I read somewhere that there was a Saint Hedwig in history who was the patron saint of orphans and we know that Jo Rowling's good at taking names from myth and history and inserting them in her books for a deeper meaning to their character. Hedwig's looking after Harry thus far makes sense therefore - I mean she flies to France in book 3 to get Hermione's present for Harry. So, possibily Hedwig will have a big part to play in book 7.