iPhone sales have doubled during the year and the Apple smartphone has reached 30 percent market share, according to an In-Stat report based on a survey of 4,255 U.S. smartphone users. iPhone sales have doubled this year, rising from 13.7 million to 24 million in 2009. At the same time, the smartphone market as a whole doubled, according to the survey, which reports that 39 percent of people polled owned a smartphone. The competition between Apple and Research in Motion, makers of BlackBerry, is not as sexy as the one between Windows and Macs, but the iPhone continues to cut into Blackberry’s market share, which has fallen to 40 percent, its lowest in two years.

The other smartphone makers are struggling as well against the iPhone. Nokia reported its first net loss earlier this month, and has introduced a high-profile lawsuit against Apple, seeking royalties for 10 patents the Finnish telecom company claims were used for the iPhone.

Nokia’s market share fell from 41 percent to 35 percent in the span of three months.

Palm, whose Pre has been a massive disappointment, continues to have a 7 percent market share, as the company has remained steady throughout the year. The massive hype surrounding the device’s announcement at the Consumer Electronics Show in January and its subsequent lackluster performance is a double blow to Palm.

So the only sure thing about the smartphone market is the iPhone, which is cannibalizing everything in its sight.

We have no idea what’s going to happen in the next 12-18 months, as competition between smartphone vendors becomes a lot stiffer – it seems like every day there’s reports of a new smartphone about to hit the market. AT&T losing iPhone exclusivity will undoubtedly drive a swath of consumers to the device.

In-Stat predicts that the smartphone market will ship 412 million units in 2014.

By Mark Alvarez