WhatsApp just posted on their blog about their latest policy changes to iPhone version of WhatsApp.
In the iPhone v2.10.1 release notes, it is mentioned that iPhone users now will join the ranks of Android users where they will enjoy the first year for free and pay 99 cents thereafter. Current users of iPhone WhatApp will use it free of charge for the rest of their life.
Secondly, users can now backup their message history to iCloud. On your iPhone, go into ‘WhatsApp Settings > Chat Settings > Chat Backup’ if you want to back up your conversation history. When you reinstall the app, you will be prompted to restore from iCloud during the initialization process.
Third, since we’re engineers at heart, we’ve introduced developer hooks into WhatsApp. We’ve had many other iOS developers ask us for API hooks to make interfacing with WhatsApp easy. Now you can do that. Learn more at http://www.whatsapp.com/faq/en/iphone/23559013