"It seems that Microsoft has been unable to meet the rampant demand for Xbox 360 hardware in the US, with retailers in the States and Canada claiming the recent shipment – only the second since launch – barely scratching the surface of unfulfilled pre-orders.
Retailers contacted throughout the US today paint a mixed picture with several major chains seemingly unaware that a refreshed stock was due. GameSpot reports that some online retail outlets are refusing so commit to a delivery date before March of 2006, surprising news though likely to reflect a strategy of under-promise and over-delivery, pun not intended." [link]