On the game's Amazon product page, the box art indicates the presence of the "Creature Creator Trial Version" as a bonus feature. This same bonus is stated in the product description. If Amazon is to be trusted, we still don't know whether the "trial version" indicates a limited demo of the soon-to-be-released creature editor, or whether the editor is considered to be a "trial version" of Spore.
We also don't know if this is EA's only intended method of distribution for the Creature Creator. We've contacted EA for further clarification, and will let you know once we have a few more facts.