Spooncraft

News of the Blizzard Authenticator isn’t necessarily bad, however. There’s no plan to expand this security to all accounts for free.

We currently have only the intention of releasing the authenticator to provide an extra layer of end-user security for those interested in purchasing it. The idea is not to punish players who do not purchase this; but rather, to provide additional account protection for those who do. (src)

Personally, I’m still buying one.