The discrepancy between software sales of the PS3 and 360 is simple. Almost 60% of all 360's are sold in the United States. America is the largest consumer economy in the world. We are likely to spend more for our entertainment so it is no surprise that that software sells more on the 360. Just look at the American software sales for specific IPs, it tells the whole story.
The PS3 will end this generation as the second most shipped console, but the 360, by virtue of being an American console and selling more 360's in the US than any other region in the world will almost always sell more software.
I simply don't understand this fight between shipped vs. sold. Sony is not going to ship more consoles than they plan on selling. Simple.
2011 Predictions
Wii: 17m (100 million total)
360: 13m (63 million total)
PS3: 15m (61 million total)
