The Federal Communications Commission (FCC) just approved Sony Ericsson's Xperia X1 for release in this country. All devices that use U.S. airwaves must receive a thumbs up from the FCC before shipping here.

Just about the only new info the docs on the FCC site reveal about the Xperia X1 is that'll ship here with the only a 3G band suitable for AT&T's high-speed cellular-wireless data network. T-Mobile users, should there ever be any, will have to make do with the far slower EDGE technology.

Keep in mind, FCC approval doesn't guarantee a smartphone will ship here soon or, in some cases, ever. While this particular device will, almost certainly, make it to the U.S., we still have no idea when that will happen.

At the CTIA Wireless Show last month, Sony Ericsson said the Xperia X1 would ship in the UK, Germany and Sweden by the end of September. After those countries, the company's first Windows Mobile smartphone is set to find its way to many other countries throughout the fourth quarter.

Sony Ericsson said availability dates for North America, China, Australia and Russia would be announced in the coming months, however.

Last month, Sony Ericsson released a software development kit (SDK) to allow developers to try their hand at building Xperia X1 Panels and applications. For the Xperia X1, Sony Ericsson developed a proprietary panel interface to run on top of Windows Mobile 6.1.

The Panels are lightweight applications that extend the phone's 'Today Screen' API to provide a fully customizable user interface on the XPERIA X1. The SDK will be available for free.

In addition to Windows Mobile, the Xperia X1 sports a unique arc slider design. So when you slide up the smartphone's high-resolution 3-inch, WVGA (840 x 480-pixel) touch screen, a wide QWERTY thumb-keyboard is revealed.

For more on the Xperia X1, see the articles below.