I think we need to understand one point: MS or SONY are console manufacturers. They are not resellers. For them, the shipment means sales. Just read their FY report, their projection is focused on how many consoles sold to resellers, but not the quantity sold to consumers. For us, we always refer "sold to resellers" as "shipped".
So if XBOX360 was shipped more than PS3 in the past year, then MS of course can claim XBOX360 is the best selling console in 2011. If PS3 was shipped more than 360, SONY can do the same thing.
I don't why people here pay such huge attention to the numbers of sold to consumers. In fact, shipment figure is way more important than retail figure to indicate which company has the most sales.
Maybe we need to open a new tread to discuss which console is the best shipping console in 2011.