Reports Compilation Assert That iPhone Beats Windows Mobile and Symbian in North America

Before Christmas came along, Daniel Dilger wrote a comprehensive piece on the iPhone's performance in North America vis-à-vis Windows Mobile and Symbian. He points out that despite the iPhone's unavailability in "significant markets" and other areas where AT&T has not or cannot establish a presence, it has managed to capture over a quarter of market share in the said area.
It's interesting to see that, according to the data compiled by Mr. Dilger, despite Nokia pouring money into the country, their presence in the US has actually shrunk. To be fair, despite the veneer of a balanced tone, it seems that Mr. Dilger can barely contain his enthusiasm for the iPhone's outstanding performance, even portraying Steve Ballmer in one of his graphs unflatteringly.
The apparent defeat of Windows Mobile notwithstanding, could it be that this development highlights weaknesses in Nokia's first-place armor? Or is the iPhone's performance tied to Apple's consistently strong marketing approach towards the US market?