Here is an interview that also states Spore is being created for the Wii and DS. (sorry the other thread was too old to reply to)
Will Wright (creator of SimCity, Sims, and Spore) did an interview with a british newspaper and it was posted over at gamasutra.com (see link above)
In the interview he praises the Wii for being next-gen due to its innovation and ability to grab new players.
“The only next gen system I've seen is the Wii – the PS3 and the Xbox 360 feel like better versions of the last, but pretty much the same game with incremental improvement,”
Asked what game set-up he had at home Wright answered: “We've got an Xbox 360 collecting dust in the background, a Wii hooked up that we use quite a bit. I don't have a PS3. I still, for the most part, prefer playing games on the computer – to me the mouse is the best input device ever.”
“Every generation it's like ‘the PC's dead! The PC's dead!’. But it carries on growing when consoles are flat for five years. At the moment I can get better graphics on my PC than I can on the PS3,” said Wright.
Wright’s personal platform preferences can seen to be reflected in his games, with his major titles such as SimCity, The Sims and the forthcoming Spore all being primarily developed for the PC. However, SimCity did prove an influential hit on the SNES and versions of Spore are planned for both the Wii and Nintendo DS.