Facebook on Tuesday released a new version of its mobile platform. A new Android version of the Messenger app doesn't require a user to sign up for a Facebook account. That's a change in tactic for a company whose hydra-like growth model is based on extending tendrils into to just about every site with a social vector. For now, the app is available only to owners of Android phones in limited countries but will roll out to others. Extending the analogy, Hydrae (the real ones) are biologically immortal. The one from Greek mythology? When you cut off a head, three grow back.