During an interview between Next Generation and Nintendo of America’s Marketing Chief George Harrison, some talk was mustered on the subject of Wii production, concluding the amount of units being created on a monthly basis:

We’re at a rate now worldwide of about 1.8 million Wiis produced every month, and that’s going to sustain itself until we get on top of this. We’re trying to make decisions on almost a weekly basis about which market to ship the product to, because in Japan it’s a big success, and same in Europe.

Nintendo is also making decisions into how much of the share of units goes to the different markets. Each territories are doing their part fairly well and they need their share of the available production.

Source: Next Generation