Silicon Valley Insider points to a commenter called Tantrum responding to a story in the New York Times about the current shortage of iPhones in Apple’s US shops. It seems that among the factors driving incredible demand in emerging markets is that the US $ price of the iPhone compares favourably compared to the local price of high-end Nokia and Blackberries.

Demand for iPhones outside the United States, particularly in emerging markets, is out of control and has reached the point where it has started to impact Apple’s normalized supply chain projections.

Follow either link for the full analysis which makes very interesting reading.
The conclusion:

Apple has produced a product that is promising but short of the mark in 3G Western Europe, reasonably good for the US but a smash hit in emerging markets.