For those of you that own an iphone and need an authenicator or an alternative to the big ol' keychain one this is now out in the app store free of charge. The only requirement is moving/converting your account to the new battle.net.
I've just got it and it seems to work well. The only major issue is if your iPhone crashes and if you have to restore the settings the serial number resets and locks you out of your account so hopefully this would be fixed.