For those of you doubting the shipping thing, if you actually take the time to research, you will find that Sony did the same thing for the PS3 during launch christmas. They had received a huge amount of flak for the supply issues and started to do air freight shipping on the PS3's direct from the factory to get more supply to the retailers.
The difference between that and the wii is that the PS3 demand died away in January and so they had tons of spare inventory and therefore sales in January were limited by demand rather than supply. The Wii is the opposite, the demand in January is still high and thus supply became even more of a problem than normal.
There's also the chance of them holding some supply back for the launch of Smash Bros in Japan, we've seen several instances of them doing that for big games last year.