Let's put this in perspective. Sony plans to have between 400,000 - 600,000 consoles ready for the North American launch (and about the same number for Japan). Of course, Sony is keeping this under wraps because of all of the problems they are having with production of the blu-ray.
Last year, Microsoft had about 500,000 consoles ready for the North American launch and we all know how that went...unless you were lucky, you didn't get a 360 until March of this year. Currently MS has sold about 5 million 360s and plans to have sold 10 million by the end of this year.
Nintendo, on the other hand, looks poised to have 4 million ready to go at launch (maybe more) and will have millions more by the end of the year. If they have 9 million ready to go by early next year, that would be amazing.
Just think, in one month's time, Nintendo may sell 5 million Wiis, something that took MS 8 months to accomplish. And, with the production problems of the PS3, we all know that it will be well into next year before the PS3 is in stock at major stores.
This all means one thing: Nintendo is going to absolutely dominate this holiday season. Sure, MS should reduce the price of the 360 to help it compete (and it's a great system, so it will do well) but the groundswell of hype behind the Wii is only going to continue to grow (it's the media darling). It will be the must-have holiday gift. What's most important is that people may actually be able to get one.