http://www.youtube.com/watch?v=T8dvMDFOFnA Original E3 2005 version.
http://www.youtube.com/watch?v=IQvswZ39vq0&feature=related E3 2006 version.
Already you can clearly see they toned down the creature physics a lot. You can also see how they chopped it up in stages and how cities are now completely round. There's still a hut editor, though. I think they might release it later, like the flora editor.
http://www.youtube.com/watch?v=F0_U9Tx17RA&feature=PlayList&p=F1065344C887EA68&playnext=1&index=19 E3 2007 version.
Here you can see the cell stage as it is now. Most stages already look a lot like they are now. You could still beam down in Space stage though, but I think they just shoved that into the expansion.
So anyways, I guess what I'm trying to say is, that some people here shouldn't be allowed to argue on the internet. I could easily find videos showing the development of Spore year after year, yet somehow people moan about noone releasing videos one week before Spore came out. I mean, come on.
Of course they didn't list all the things they had to cut, and of course they set up all kinds of interesting scenarios, camera angles and hacked in a few incomplete features that might not be feasible in the long run. They have to sell their game, in all its aspects, before it's even finished. I bet Will Wright spent hours practicing putting together a creature that wouldn't glitch terribly when walking because the scripts weren't finished yet.
Even though Spore could have been a lot better, it's still here and it's still successful. This means other companies will likely copy it and improve on it. In only a few years we'll have RTS games where you get to design your own structures, ships and units, RPG's where you can design your own summons, mutated trees, you name it. There's already a few games that do that.
The technology could even be used to allow other game developers to import a sort of "Creature Creator Library" and the like into their code so they can use the creature creator to design the monsters for the game, and the library does all the texturing and animating for them. That'd be awesome if done right.