Ok, so it’s not Blackberry Messenger for iPhone, but it’s the closest thing. What’s App is an instant messaging client for iPhones and Blackberry smartphones.
WhatsApp is a smartphone-to-smartphone messenger/chat application. WhatsApp allows you to carry on a conversation in real time with your mobile contacts without having to pay for SMS. WhatsApp Messenger is currently available for iPhone and BlackBerry and yes, iPhone and BlackBerry owners can message each other!
I’ve been using it for a while now, and I must admit it’s a pretty neat application.