BeyondGenius.com

Even after being on the market for less than half a year, more iPhones sold in the fourth quarter than Windows Mobile phones in the U.S., according to research from Canalys.

Canalys researchers estimate that the iPhone had 28 percent of the U.S. converged-device market in the fourth quarter of 2007. Research In Motion, with 41 percent, had the largest share of the market. Windows Mobile phones had 21 percent share of devices sold in the quarter, falling into third place behind Apple.

Worldwide, the lineup is a bit different. Nokia, which typically dominates around the world but not in the U.S., sold 52.9 percent of smart phones worldwide in the fourth quarter. RIM grew its share of converged-device sales to 11.4 percent, up 121 percent over the same quarter in 2006. Despite its limited availability around the world, Apple took third place with 6.5 percent of the market, just barely squeaking ahead of struggling Motorola.

In Asia Pacific, Motorola had a drop of 28 percent in its Linux smart phone shipments compared to 2006.

Motorola said Thursday that it was considering separating the handset unit from its other businesses in an effort to snap a deep slump since its meteoric success with the Razr.

Motorola said in a statement that separating the mobile devices business, which is dominated by cellphones, would “permit each business to grow and better serve its customers.” Its smaller businesses are home and networks, which sells TV set-top boxes and modems, and enterprise mobility solutions, which sells computing and communications equipment to businesses.

“We are exploring ways in which our mobile devices business can accelerate its recovery and retain and attract talent while enabling our shareholders to realize the value of this great franchise,” chief executive Greg Brown said in the company’s statement.