For anyone who didn't manage to pick up a Diablo 3 CD key or can't find one in store, there is a work-around to purchase the game from Blizzard at $59 USD as opposed to $79 for the AUD key.
What you need to do is have a battle.net AUS account already set up and call the Australian Blizzard contact number
1-800-041-378.
Once you call through to the operator tell them you have trouble purchasing the game on your computer and would like them to put it through for you.
Make sure you ask them to buy the game for you, not add a credit card to your account.
They will then charge you the $59 USD and you need to make payment using your credit card.
Cheaper than buying CD keys and you're guaranteed to get it as opposed to it being sold out in retail stores.
http://img265.imageshack.us/img265/9508/blizzl.jpg <- screenshot of my purchase
Be aware that the opening hours for the contact center are 19:30 - 14:00 AEST, 7 days a week
19:30 - 14:00 AEST, what time is that?