If anyone out there does it, feel free to post your findings to http://imfreedom.org/.
I'd be willing to bet that WhatsApp has some competent programmers, and looks very similar to how Apple's built iMessage. I think everyone is entitled to the most security possible, but unfortunately when you're at the scale of WhatsApp, perfect security would make all that ultra-tantalizing data pretty hard to analyze. They're a business, they have a responsibility to their investors to grow the business, and data right now is a _big_ business.