For just a moment, consider the numbers.
Recently, a Sony financial report stated that 3.7 million PlayStation 3 units had been sold worldwide in the second fiscal quarter of 2011.
That brings the global total to 55.5 million units . Last month, Microsoft said they had shipped 57.6 million units of the Xbox 360 worldwide. Now, Sony counts its number as "sales" but it's tough to determine if they're referring to the actual sell-through number or the sell-in (shipment) statistic. As you can see, Microsoft counts the shipped numbers.
Therefore, even if we assume the worst and say Sony's 55.5 million is a shipped number, we have to consider a few factors: firstly, there's no doubt that the 360 has had terrible reliability in the past, thereby resulting in a whole lot of sales to the same consumer (I don't know anyone who hasn't gone through at least three 360s since 2005). The sales number doesn't change, of course, but in terms of new customers , it seems obvious that the PS3 has seen more.
Also, have we all forgotten that the 360 launched a full year before the PS3? Even if both are shipped numbers, that's 57.6 million 360s shipped in 6 years, while it's 55.5 million PS3s shipped in 5 years . Therefore, if we remove the first 360 year where it had no competition, the PS3 has indeed sold more in head-to-head competition. Interesting stats, no?