Not long after announcing a partnership with Microsoft, Sony Ericsson announced its latest smart phone today, and it’s the first one to offer a Windows Mobile operating system. Meet the XPERIA X1. The X1 has a large 800×480 resolution screen, although the physical dimensions of it aren’t currently available. It weighs in at 5.1 oz and measures 4.3 x .7 x 2.1 inches in size, and although it looks like it could offer a touch screen, a full QWERTY keyboard slides out along its vertical axis. The phone also supports an increasingly popular video calling feature, using its 3.2-MP camera. The X1 also supports stereo Bluetooth, has built-in aGPS, and an FM radio. Other features include an optical joystick for navigation which will allow you to swipe your finger across the navigation screen to move the pointer on the display. Sounds similar to a track pad to us. The interface uses “XPERIA” panels for displaying different content like Web sites or multimedia files directly on the desktop, which shows that Sony Ericsson , like HTC, has opted to create a custom Windows Mobile experience. It supports the following netwroks: GSM 850, GSM 900, GSM 1800, GSM 1900, EDGE< HSDPA, HSUPAm, UMTS 850, UMTS 900, UMTS 1700, UMTS 1900, and UMTS 2100. Looks like it could make a good choice for anyone in the states looking for a large and unique touch screen phone on their 3G network.