The Creature Creator is a standalone utility that is pulled directly from the game. It allows you to have a kick-awesome time building creatures before the game comes out, and then you can import them to the game itself.
It comes out in six days. I can't wait.
There's a free demo with 25% of the parts and a $9.99 full version with every part that's in the final game. I'm probably just going to get the demo, as I don't like paying for things twice.