Back in 2006 both Nintendo and Sony stated in public that they were switching to reporting actual sales to customer numbers. Googling only finds references to the original statements by Nintendo and Sony and not the original statements.
However, just a month or so ago Sony once again reiterated that they only report actual sales:
"We calculate our install base by 'sell through' and have done for the last four years I believe", we asked for a little additional clarification...
"We classify 'sell through' as the number of units consumers have actually purchased from retail. 'Sell in' is the number of units we've sold to retail."
Didn't check for a recent statement by Nintendo, but I assume they still report actual sales.
Microsoft remains the only one who still tries to pass off their shipments of stock to retailers as actual sales to customers. Basically pads the worldwide installed base of the Xbox 360 by a couple million units.