Being popular is tough! Today at a Tokyo briefing, Nintendo prez. Satoru Iwata promised that Nintendo was doing everything possible to get increased Wii hardware on shelves. Said Iwata:

We must do our best to fix this abnormal lack of stock. We have not been able to properly foresee demand.

While Iwata did not disclose the Wii's production capacity, he did announce that 2.5 million DSes were being produced monthly in order to meet the insane demand. That's the highest production for Nintendo hardware. Ever. Forecasts for this year include selling loads of games, consoles and making a shit load of money. Brian Ashcraft

Nintendo Increase Wii Production [Famitsu]
AP Story [Houston Chronicle via Game Industry]