If you've been tingling with anticipation over the forthcoming Windows Phone 7 handsets, Engadget just caught wind of a very promising Dell device. The phone, dubbed Lightning, is a portrait slider with a spec sheet to back up its name.

According to the leaked documents, Dell's Lightning boasts a 4.1-inch WVGA (800x480) OLED display, a 1GHz QSD8250 Snapdragon processor, 1GB of Flash memory with 512 MB of RAM and 8GB of storage via microSD (presumably built-in).

It also has a full QWERTY keyboard, a five-megapixel autofocus camera (possibly with flash), 802.11b/g/n Wi-Fi, Bluetooth 2.1 EDR, GPS, an accelerometer, a compass, FM radio, as well as support for Flash, Silverlight, and various popular audio and video formats.

The Dell Lightning is destined for AT&T and T-Mobile, and is expected to arrive in the fourth quarter of this year along with a volley of other Windows Phone 7 devices.