Facebook has just launched a new feature on their message app, unlimited calling. You can now use WiFi to chat on the phone with your friends. This is a huge feature upgrade to their message app and a great idea. Lookout Spring, Verizon, AT&T & T Mobile...Facebook is knocking at your door. With an increase in WiFi and internet everywhere, technologies like this are becoming easier and easier to integrate.
Also on a side note, maybe the purchase of WhatsApp had something to do with this? Overall, great work and upgrade on Facebook for integrating this feature!