Sony Ericsson introduced the Xperia1model in February, saying it would start to sell the phone in the second half of 2008 in selected markets.

On Monday, and over the weekend, several technology blogs, and Swedish daily Dagens Nyheter, reported of delays in product rollout, quoting rumors and unnamed sources at Sony Ericsson.

“There is absolutely no delay. The product is on track,” Sony Ericsson spokeswoman Merran Wrigley said. “We have said it will roll out in Q4, and we are on target to do that.”

Phone makers usually unveil new models months ahead of starting sales–to inform operators and consumers–but introducing new phones more than six months ahead of sales is relatively uncommon.

With Sony Ericsson joining the list of Windows users, all the world’s top handset makers apart from Nokia will offer Windows Mobile phones.

Despite years of investments, Microsoft has struggled to appeal to mobile users, and has won only around 10 percent market share among smartphones.

Stiff competition from other platforms–especially RIM’s BlackBerry and Apples iPhone–have hurt demand for Microsoft-based products, and the U.S. software firm missed its 20 million phone sales target for the year to June 2008.

“The challenge for manufacturers is that Windows Mobile 6.1 is struggling to meet the high expectations that devices like the iPhone have set for top-tier phones,” said Ben Wood, research director at CCS Insight.

“To try and overcome its shortcomings we’ve seen companies like HTC, Samsung, and now Sony Ericsson go to great lengths to re-skin Windows Mobile in order to deliver something that is more appealing to mainstream consumers,” Wood said…!!!