My mistake. I meant the third quarter of 2011. Actually, the 3GS was the #2 best selling smart phone for the second and third quarters of 2011.
That is also on the iPhone's first carrier and can't be directly compared to verizon, who arguably has a stronger android line-up. A particular model of the iphone can be the single best selling smartphone while getting trounced by the competition because there are so many other handsets. It's much different to say that a/all iPhones are outselling ALL other smartphones by a 2:1 margin. And that's how marketshare is measured, not by specific phone, but by phone OS.