It wouldn't be a surprise if Apple expects to exhaust that supply of 4 million within just a few months, either. If you recall, at the beginning of this year Apple made it known that they had sold 4.4 million iPhones in the last quarter of 2008 alone, with the total number of units sold probably approaching 20 million at this point. Where they were just a blip on the radar for the first year, they are now making up a significant portion of new smartphone sales, which will obviously result in a market share increase.
The highly successful iPhone App store no doubt has played a significant part in the iPhone's success. On the other hand, Google's own Android, along with its App store, hasn't been quite the sensation most hoped for. They also did not have a massive marketing campaign behind it, however. Is it too late for Google to catch up?