Facebook today unveiled what CEO Mark Zuckerberg called the "next version" of the social networking site. Facebook Home is a new UI for Android devices that transforms a user's smartphone or tablet into a central hub for Facebook. When asked if Home will also be available for iOS devices Zuckerberg replied, “Apple is a very controlled environment". Meaning you will probably never see Home on your iPhone or iPad.
The Home interface is just too invasive for Apple's closed ecosystem. When installed, it takes over a device's lock screen, home screen and even notifications. This is something Apple would never allow. Zuckerberg said, Facebook has "great relationship with Apple", but that doesn't mean they will welcome a UI that overrides iOS. It's just not the way Apple does things.