Oh. Thanks for digging that up.
This quote from the post really stands out to me:
"WhatsApp runs on an incredible number of mobile platforms, so full deployment will be an incremental process as we add TextSecure protocol support into each WhatsApp client platform. We have a ways to go until all mobile platforms are fully supported, but we are moving quickly towards a world where all WhatsApp users will get end-to-end encryption by default."
It seems... unlikely that the crypto integration would be left half-done. I guess I could find a Whatsapp user with an iDevice and another with an Android device and look at the software UI for clues. :D