AT&T and Pantech announced on Monday the Pantech Duo.

This dual slide Windows smartphone supports 3G HSDPA and GRPS/EDGE Quad band connectivity.
Other features of the Pantech Duo include 2.2 inch screen with QVGA resolution, 1.3MP camera, music player, slide-out QWERTY keyboard and stereo Bluetooth.
The measurements of the Pantech Duo are 4.01 x 1.97 x 0.78 Inches. It is a bit fat for my taste, but otherwise the form factor is quite interesting considering the slide out keyboard.
The Pantech Duo is selling for $249.99 to customers who sign on for a 2-year contract.
The Mobility site has an unboxing video of the AT&T Pantech Duo. IntoMobile has a video tour of the Pantech Duo and Gizmodo has a photo gallery.