It's really amusing to consider the philosophical debates that occur in the zombie world. Remember that it's physically indistinguishable from our own world. So there's this thriving discipline called "philosophy of mind", where all the zombies sit around discussing the mystery of consciousness, and disputing the far-fetched possibility that maybe there's some distant possible world that's just like their world "except full of zombies!" ("Impossible!" another zombie replies.) Oh dear. What if that's us?
[Update: But see section 4.3 of Chalmers' article here.]