
To be honest, I have no idea if Deutsche Telekom is the only operator supporting the iPhone, but there are always models hacked to work with more carriers, so I wouldn't be able to give you accurate numbers, anyway. Here's what we know, based on Deutsche Telecom's declarations, quoted by Reuters: since the 9th of November, 70,000 iPhone customers signed up, making Apple's mobile "the most sold multimedia device in T-Mobile's portofolio", according to Philipp Humm, T-Mobile Germany's head.
At last, it's interesting to mention that France Telecom, the market leader in France, said their sales since 28th of November exceeded 70,000 iPhones. While these numbers can't compare to the US sales, they are clearly showing that the iPhone is selling well everywhere, so Apple is one the right path in the mobile world. We only need to see if they can keep it up...