Reggie has stated many times now that Nintendo is not stockpiling Wiis in a warehouse. However, Nintendo may have been inadvertently stockpiling Wiis depending on how their distribution has gone so far. For example, if they have a million units in Japan waiting to be sold, that's effectively a ~20 week stockpile at current sales rates. That means that Nintendo could either (1) change the region encoding, depending on how involved that is, and sell those to America or (2) shift production of Wiis to another region (this would require only changing the region locking step.
The region change could be as simple as flashing the firmware, which could mean Nintendo may end up the holidays with a shortage in Japan as well as everywhere else in the world if they're doing a fantastic job of (re)distributing all of their units.
There is more to console war momentum than being able to sell as much as you manufacture. If Nintendo could sell 5 million units in December, this would give them a huge boost with third parties. Further, there would be additional game sales for Nintendo themselves.
I don't think Super Mario Galaxy will ever reach a ~50% attach rate like Halo 3 did, although I suspect that H3's attach rate will decrease a little as time goes on and Mario Galaxy will maintain its ratio. More units sold may help Galaxy surpass H3 in total sales.
