I'm torn on how to respond to this. At my work I admit that the 360 section is much larger than the PS3 section. And in my region there are about 5 other of our chain that likewise have the same set up. But like I said before, this is because the 360 was released prior to the PS3.
When PS3 was first launched, I was working at the store, and yes it was a measly line up. 360 got many exclusives that PS3 did not. But now when you line them up:
360: Halo, Gears of War, Left 4 Dead, etc.
PS3: LittleBigPlanet, Killzone, Infamous, Ratchet, etc.
The big games like COD, Dead Rising 2, Mass Effect 3, Borderlands, Resident Evil, etc. All these games are released for both systems. Why? Microsoft couldn't capitalize on their sales quickly enough to snuff out Sony's lackluster launch and now they run about even.
The only claim 360 users can say is that they've been around a little longer and that's why more people own 360 than PS3. However I think if you came to my work you'd be surprised how many 360 users are turning to the Sony side.
And as far as sales... Nintendo kind of trumps all and they didn't even need next gen graphics.