by , 2:50 PM EDT, March 31st, 2008

Piper Jaffray analyst Gene Munster has reiterated his estimate for 45 million iPhone sales in 2009. He believes the iPhone is Apple's driver with the greatest potential, and the iPod will be a slower growing segment. New iPhone models with more features and lower average selling price (ASP) will drive significant unit growth, according to Mr. Munster.

In a note to investors obtained by iPO, Mr. Munster outlines three distinct growth drivers. "First, we believe the iPhone will replace the as a driver of significant growth for the company," he wrote. "Second, Apple's growth is powered by the Mac business, which is steadily gaining share in the PC market. And third, we believe the iPod segment will remain a growing business as Apple adds compelling new features at lower prices over the coming months," Mr. Munster wrote.

Mr. Munster admitted that most other investors view his estimate of 45M iPhone sales in CY2009 as aggressive, but he is maintaining that estimate. He expects Apple to roll out a 3G iPhone in the next 3-6 months, offer an entire family of iPhones with two to three separate models by January 2009 and include lower priced models. The addressable market will double every year for the next two years, he predicted.

The estimate is based on an expansive international rollout of the iPhone, and China will be an important factor, Mr. Munster said. "We continue to believe Apple is on track to release the iPhone in Asia in CY08 (likely in Japan). In China, however, the market dynamics complicate Apple's business model of exclusivity and we believe the company will likely need to alter its terms in order to launch the iPhone with a Chinese carrier like China Mobile (over 370M subs) by mid-CY09."

The Piper Jaffray analyst maintained a Buy rating and a 12 month target price of US$250.00.

In afternoon trading, AAPL was at US$143.60, +$0.59.

In the interest of full disclosure, the author holds a small share in AAPL stock that was not an influence in the creation of this article.