It might be difficult to find out how many iPhones are being connected to carriers other than Apple's partners, but statistics are available for web use.
Net Applications' Market Share report reveals that "The iPhone has a presence in almost every country on earth."
The analysis shows the 'market share' of the iPhone's Safari browser in different countries. As you'd expect, it is small - less than 0.1 percent for most nations.
The device is most established in the US in terms of official sales, and this is reflected in a 0.2 percent share in Net Applications' stats.