Remember Dell Lightning? Well, the handset’s back and got turned into Dell Venue Pro, the most promising Windows Phone 7 smartphone unveiled today. Although we only managed to get hold of a partial specs list, we saw Engadget’s fun time with the device and it certainly is a great piece of work. The format is a tad unusual though: portrait slider with a huge touchscreen.

Dell Venue Pro packs a 4.1 inch WVGA AMOLED touchscreen display, based on Gorilla Glass technology and supporting multitouch. Design-wise, the handset reminds us of the Dell Thunder, an Android-based model. Engadget mentions that Venue Pro comes with rounded chrome sides and a grippy feel, plus a responsive touch-sensitive buttons.

You also get a 5MP camera with flash, a great slide out QWERTY keyboard, that’s a bit similar to the one on Droid 2 (as far as buttons are concerned) and a Snapdragon CPU. This baby will be coming to T-Mobile in time for the holidays and also through Dell’s retailing partners. Apparently, the phone won’t reach AT&T, since T-Mobile is the exclusive partner for the WP7 handset.