"We definitely expect we will trail in February as a result of our supply constraints. By April, we will be in a very healthy inventory situation."
http://kotaku.com/367231/microsoft-expecting-low-360-sales-in-feb-march
Nomatter if you buy their provided reasoning, an interesting comment for VGChartz' hardware tracking for North America.
Here in the Netherlands shops seem overstocked and 360s are selling slowly.
[edit] There's already a thread about this, sorry. How about bringing back the forum search option ioi?
http://www.vgchartz.com/forum/thread.php?id=20371&start=0