The Windows Mobile smartphone from Sony Ericsson, which has a unique "panels" user interface, will become available at the end of the month. Too bad it won't be sold in the U.S.The Xperia X1 was first announced at the Mobile World Congress show back in February. Ever since, Sony Ericsson has been toiling away to meets its slated fourth quarter release date. The phone will start shipping overseas on September 30, but won't be available in the U.S directly -- even though it supports U.S. 3G networks. The Xperia X1 is the first product under Sony Ericsson's new premium sub-brand Xperia. Designed to meet consumers needs for a converged entertainment and mobile web communication experience, the Xperia X1 is encased in a real stainless steel body, with an arc-slider design. "We are extremely pleased with the innovation and new user experience we have created for consumers on the Xperia X1," said Rikko Sakaguchi CVP and Head of Creation and Development at Sony Ericsson in a prepared statement. "The in-depth demonstration on the web cast will showcase how this handset is truly unique. The nine panel eco system puts the user in total control of the primary experiences available on the phone and allows consumers to personalise the panel interface to suit their needs and lifestyle. The Xperia X1 has the highest quality screen on the market, four-way navigation keys and optical joy stick to give a stressless browsing experience and, with its super fast processor and network speed the Xperia X1 really bridges the gap between personal, entertainment and work mobile needs." Sony Ericsson did not provide a release date for the Xperia in the U.S., though it is positioned well for AT&T's network. AT&T has not said that it will sell or market the Xperia, but it certainly could. Perhaps Sony Ericsson and AT&T haven't been able to come to an agreement yet about its release here in the U.S. For Sony Ericsson's sake, I hope they get it to the U.S. soon.