Oh Jesus Mike B will be here any moment... He loves his shipment numbers.
It's quite clear Sony expected higher sales and there shipment numbers reflect this... unfortunately they didnt achieve these sales. npd confirmed this also.
Actually Sony said they won't alter their FY sales estimate, so it's probably on par with expectations.
And yes, worldwide sold to retail data is the most concrete and exact data we can get on actaul worldwide console sales.
Japan tracking is easy for VGChartz as 3rd party data is usually out before VGChartz data. North American and UK data is harder, but there are usually good NPD and Chart Track indicators, they happen to be the 360's strongest performing markets. Much of interest with regard to PS3 are the rest of the world, where the PS3 performs pretty well.