WhatsApp is making things a little more secure with two-step authentication, which is rolling out now to the WhatsApp beta app for Windows Phone. As seen in the screenshots below, WhatsApp beta users are now seeing the option in the Account portion of the app's Settings menu.
Once enabled, users can set a passcode, which will then be required whenever someone tries to register WhatsApp to a number on a new device. There are also options to change the passcode or disable it altogether after it has been set up.
While this may seem like a minor addition on the surface, it's a huge and much needed feature for keeping your account out of the hands of others. While only available in version 2.16.280 of the WhatsApp beta, hopefully two-step authentication will make its way to the release version relatively soon.
Thanks to Dave for the tip and screenshots!