At the time of this writing, the Blizzard Authenticator is marked as sold out. It isn’t entirely clear whether I missed the opportunity to buy it this morning (and they’ve gone like hot cakes) or they haven’t actually yet been offered for purchasing.
If it’s indeed the former, Blizzard needs to take preorders ASAP. If they’re already sold out, it is quite clear everyone is feeling, like me, that it has instantly become a mandatory tool to increase your account security.
EDIT: Looks like I’m not alone with this disappointment. Siha at Banana Shoulders echoes the sentiment.