According to this IGN interview, a free trial version of the Spore Creature Creator will be released in June. It’ll contain a quarter of the final game features, but there’ll be a retail version as well, which will contain the full creature creation kit.
“A trial version of the Spore Creature creator will be available for free through a variety of sources including as a download from Spore.com and in The SimCity Box,” said Maxis’ Patrick Buechner. “There will also be a version of the Creature Creator available at retail. The free Creature Creator has about 25-percent of the creature making parts from Spore. The retail version will have 100 percent. It’s up to the players to choose which version they want, but they’ll all be available at approximately the same time.”
More through the link. No word on how any of this affects Europe. Spore hits in September.