I have another question in this vein though. If Body Double comes into play as a clone (any cloning creature actually) does that clone come into play as something already in play?
Well, Body Double specifies the graveyard, but in general the answer is yes.
In fact, as far as I can tell (Gatherer's text search function being limited as it is) Oracle card text will always specify a zone, which is usually the battlefield.
Edit: Oh wow. Alpha Clone even specifies that the copied creature must be in play.