A new preview can be found at CVG with some insight of new details for Spore. One of the most interesting new details is the fact that the game will create huge versions (hundred-foot high forms) of the creatures that you created for you to battle with. You know what this means, don’t you?
You’ll occasionally run into an Epic. At the microbe stage, it’s the four-eyed fish that fills the screen. At the tribe stage, it’s a mountain-sized giant stomping your village. But the game doesn’t have pre-designed bosses, it just takes one of the species it knows and makes it much, much bigger. That includes yours. So that race of fanged bunnies you experimented with on your first time through may come back to haunt you in hundred-foot-high form.