Frequent Apple (NSDQ: AAPL) forecaster Gene Munster, an analyst with Piper Jaffray, has come out with a whopper of a prediction that dwarfs many of his previous iPhone guesses. He’s expecting Apple to sell 13 million iPhone 3Gs this year and 45 million next year, BusinessWeek reports. On the lower end, other analysts are guessing Apple will sell around 11 million iPhones in 2008 and another 25 million in 2009.

If Munster proves to be right, Apple would outpace the number of Windows Mobile smartphones shipped worldwide a year after releasing its first 3G device. Microsoft (NSDQ: MSFT) said it sold 18 million Windows Mobile licenses in the fiscal year ended June 2008, missing expectations by 2 million. Some say that will make it even harder for Microsoft to hit its goal of increasing global sales in fiscal 2009 to 30 million, which is still easily shy of Munster’s forecast. But maybe Microsoft has a sleeper surprise that could help it reclaim some of its lost share—don’t forget it bought Danger, the Sidekick maker.

Nonetheless, it would be quite a feat if Apple, which had zero market share little more than a year ago, is able to knock out Microsoft’s global position by the end of 2009. Apple doesn’t appear to be letting up in the slightest, but it would be major victory by all accounts. According to figures published by Symbian after Apple’s first full quarter of iPhone sales, Apple climbed past the smartphone market share positions held by Microsoft, Symbian, Linux and Palm (NSDQ: PALM) OS in the U.S. with a 27 percent share. BusinessWeek goes on to report that Apple plans to build 40 million to 45 million iPhone 3Gs over the next 12 months, which would even eclipse Munster’s sales prediction. Apple declined to comment and only repeated its goal of selling 10 million iPhones by the end of this year.

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