Will definitely be interesting to see how this ultimately plays out. While right now we can arguably define BBM as a cross platform messaging application and use WhatsApp, Viber, and the like as comparables, it seems like the direction they are heading is to more of a social media network. As such, there is quite a long way to go and a lot of mass adoption that has to occur to put it in the same conversation as a Twitter. The main difference is that a free cross platform messaging app is going to be tough to monetize, compared to a social media network.