There's a new video of Will Wright explaining Spore in a bit more depth on GT today. It's below, so click away to have a look. Make sure to keep an eye on the screen behind Wright, which shows quite a lot of footage of the spaceship creator. It is one of eight creating tools in the game, along with the Creature Creator.
Now, if you're me, you're still a bit confused about how the Creature Creator fits in with all this. If I start with a unicellular lifeform, and evolve gradually, then when does starting with a blob and making a creature come in? Kieron seems to have a better grasp on it all, suggesting that it's something you come back to as you earn more Spore "money" - something the released Creator gives you in abundance at the start. He puts it best by saying, "Think of it as the shop in Xenon 2."