To try to get an idea what this means, I looked at last few quarterly earnings calls as reported on iLounge. Here are the iPhones sold each quarter since their introduction:
June 2007: 270,000 (It was only on sale for two days in this quarter.)
September 2007: 1.1 million
December 2007: 2.3 million
March 2008: 1.7 million
June 2008: 717,000 (There was limited stock, as the channel was being cleared for the 3G.)
September 2008: 6.9 million
That's a hockey stick if I've ever seen one. And it's not even the holiday season yet, although problems in the broad economy might mean a weaker-than-usual holiday shopping season.
Meanwhile, iPod sales were more or less flat through that entire period at around 10 million or 11 million per quarter, with one exceptional spike to more than 20 million last holiday season. That's nothing to sneeze at, but Apple's future revenue growth is clearly going to come from the iPhone, along with any spikes in Mac sales. That's why it makes sense for Apple to concentrate its innovation in those areas and let the iPod become a simple cash cow.