With its three-inch VGA touch screen, curved slider design, and speedy network access, the Xperia X1 is one of the hottest Windows Mobile smartphone I've ever laid eyes on.

Just unveiled at the World Mobile Congress extravaganza in Barcelona, the Xperia represents Sony Ericsson's first crack at a Windows Mobile phone (until now, all of Sony Ericsson's smartphones have been powered by the Symbian OS). Let's talk about the basic specs first: it's a quad-band GSM phone (good for making calls on worldwide GSM networks), and it supports 3.5G HSDPA and HSUPA for speedy Web surfing, video streaming, and file uploading. Wi-Fi is on board, as well as a 3.2-megapixel camera and aGPS (or GPS assisted by cell-tower triangulation). Pretty nice, especially given that AT&T just announced that it's about to roll out HSUPA here in the States.

Of course, the centerpiece of the X1 is its three-inch WVGA screen—that's 800 by 480 pixels, compared to 480 by 320 pixels for the iPhone's 3.5-inch screen. The touch-sensitive screen will feature a series of Xpreria "panels" that'll give you quick access to Web sites, music, events, and the like; running underneath will be Windows Mobile 6. (It's not clear whether the phone will use the professional or pared-down standard version of Windows Mobile, but more details are expected to emerge later today.)

Also cool is the "arc-slider" design of the X1, which slides open to reveal a full-QWERTY keypad. Meanwhile, beneath the three-inch screen is a four-way navigational keypad, "Talk" and "End" buttons, a pair of soft keys, and a Windows button for calling up the Start menu. There's no stylus, interestingly enough, which leads me to believe that we're talking about the "standard" version of Windows Mobile (found on phones such as the BlackJack II).

The Xperia X1 is slated for release in the second half of the year; no details on pricing or carriers just yet, although the phone looks like a prime candidate for AT&T's lineup.

Related:
Press release