The Spore Creature Creator has now been released for both Mac and PC. From the press release:

With a simple drag-and-drop interface, you can assemble your creature, Pull and stretch parts exactly as you choose, then paint your creature with unique colors and patterns. In just a few minutes, anyone can easily make incredible animated creatures. You can share your favorites with friends using simple built-in tools, then visit the SPORE website and look at all the other cool creatures your friends and people all around the world are making.

The trial version can be downloaded here but it only contains 25% of the parts from the full version. You can purchase the full version of Creature Creator from the EA Store for $9.95 and claim back the price when you buy the full game.

Maybe this is just what I need to finally commit to Spore. I'll post some creations later tonight.