The social network Facebook (NASDAQ:FB) has announced that it's buying the popular and rapidly growing smartphone messaging app WhatsApp for $19 billion. The service allows users to send text messages for free as data, circumventing SMS costs imposed by wireless carriers. Adoption of the app is growing at a torrid pace, with the number of users having reached 450 million in the five years since WhatsApp was founded. But will it prove to be worth the amount Facebook paid for it? In the lead story on Thursday's Investor Beat, host Chris Hill and Motley Fool analyst Matt Koppenheffer discuss the deal, and highlight one major bonus to the acquisition for Facebook: keeping WhatsApp out of Google's (NASDAQ:GOOGL) hands.