Whether we go by VGC numbers of the manufacturers numbers, Xbox 360 has, up to this point, sold more consoles. No question about that. It's a simple and objective fact.
Also, it doesn't matter if the PS3 wasn't being sold when the Xbox 360 went to retail for the first time. That's life for you, it's not fair and it doesn't wait for your convenient time window.
Now, what I do find possible is the Xbox 360 actually having a very high attach ratio and less consoles in homes at the moment, being used as game machines, mainly due to the widespread RROD and the current wave of new 360 Shorts replacing old 360s. In effect, I think it's possible that the PS3 is actually, shall we say, ahead of Xbox 360 in the number of consoles with a home and being used as gaming machines. I believe there are many 360s left for dead, in transit and out on the market due to the reasons I've previously stated.
It's merely what I think is the current state of affairs, based on the assumptions that the shipment figures for both consoles are quite similar, the 360 sells mainly to a heavily hardcore american and british audience that buys a ton of games, which would justify the very high attach ratio, and the mechanical problems the 360 faced, having led to millions of replacement units, as well as the current replacements with the new 360 Short.
We can't really prove it. But it's my theory.
