Alexie, it means that Sony wanted to ship 6m by the March time period, but either couldn't make or sell that many units to retailers.
Sony cannot create more units than they can sell, or else they'd be laying off every single worker for months, as I doubt most any retailer has made any major purchase orders in the past 3 months for new units.
Realilistically, the only place that'd get new units shipped to it would be PAL territories where the PS3 is still selling at any remote level that might require more supply. Other than that, don't expect Sony official data to reflect more than 750,000 units shipped last quarter, if that.
Back from the dead, I'm afraid.







