Relax, they aren't forking Android
Today Facebook announced a whole suite of new social apps for Android that will help with staying up to date with status updates, messaging, and everything else Facebook has to offer. Don't worry, Home isn't a new operating system, or their own phone. Everything will be downloadable from Google Play. New updates with fresh features will come every month. It will be available for download on April 12 for a few select devices (Galaxy S3, Galaxy S4, HTC One X+, and Galaxy Note 2), and the newly announced HTC First.
The main idea here is that instead of apps on your home screen, it's people. There's a new way of viewing the news feed called Cover Feed which quietly flips through the visual stories coming through Facebook - this is basically your new lock screen. Everything is very finger friendly, with swipes employed to flip between stories, and double-taps to like them. The various apps can become the default apps for SMS, camera, and many other system tasks. Incoming notifications show up over your contacts, and can be dismissed with a swipe.
Chat Heads are little icons that float at the top of the screen that let users quickly pop in and out of conversations, no matter where they are - they even persist when navigating through other apps, so you can reference something while still being able to send relevant information over to friends.