The balance of power in the mobile messaging space is about to shift in a big way -- Facebook has just announced plans to acquire WhatsApp for the equivalent of $19 billion in cash and stock. The deal will see WhatsApp run semi-independently, much like Instagram. The chat service will maintain its brand and existing offices, but it will take advantage of Facebook's "expertise, resources and scale." It's safe to say that the combined entity will have a lot of clout should the deal close later this year. WhatsApp already has over 450 million active users every month; combine that with Facebook Messenger and competitors like Line suddenly appear tiny by comparison.