Sony reported 3.7 million PS3 unit sales worldwide for Q2 of fiscal year 2011 (which ended September 30), bringing its life-to-date total
to 55.5 million units and improving on its year over year Q2 sales by around 200,000. Just last month, Microsoft touted
57.6 million shipped units of the Xbox 360 worldwide, bringing Sony within sight of the vaunted number two position behind Wii (Nintendo reported
89.36 million units shipped as of October).
While Sony's document says "sales," it's difficult to tell whether that refers to sales to consumers ("sell-through") or shipments to retail ("sell-in"). Both competitors' numbers refer to shipments.