I kinda see Microsoft giving the green-light for such a Wii project. They agreed on a DS-version, albeit that is a handheld, whilst Microsoft doesn't have one. So no competition with their own stuff.
Microsoft sees the Wii's fanbase as totally different then theirs. Thus, Microsoft doesn't feel threatened by the fact that it would draw away potential 360 buyers when they'd be bringing VP to the Wii. And, not trying to be rude here, but doesn't the Viva Pinãta franchise fit the 'overall' Wii-owner better?!
THE NETHERLANDS