Ok, so this is why it's part of a big deal - 11 developers have just canceled their project for the Occulus Riff including Noth's Minecraft. Minecraft was canceled on the Riff the other day, but we didn't know why. You can read the blog here: http://notch.net/2014/03/virtual-reality-is-going-to-change-the-world/
So seems like more money from Facebook, but fewer developers want to work with FB on the project.