Graphic designer Psikopathe, of NAK Phone Design fame, has released his latest concept of an HTC smartphone, and this one is as sexy as you’d expect from the man whose last mockup, an imaginary HD3, spawned dozens of stories spinning it as possibly the real deal. The HTC HDD, as he has dubbed it, is a 4.8-inch beast of a device with an unusual 870 x 480 AMOLED display — unusual, that is, until you realize that the extra 70 vertical pixels are reserved for a row of virtual softkeys that change depending on the application.

Other specs on this dream machine are equally fantastic: 1.5 GHz dual-core Snapdragon processor (delaying imaginary production until the end of 2011, unfortunately), 1GB of both RAM and ROM, and a 32GB-capable microSD slot for expansion. But Windows Phone 7 doesn’t support memory card expansion, you say. Well that card slot is actually for Android: HDD stands for HD Dual, as in dual-boot, meaning that this wild handset is envisioned to run either WP7 or Froyo.

Compared to the above, the rest of the features on the HDD seem fairly tame, such as a ten-megapixel camera with dual-flash and 3x optical zoom, 4G cellular data, an HDMI port, and a capacious but still possibly overmatched 1800maH battery. One touch we do appreciate is the fact that when the softkeys are hidden, the screen is said to display a perfect 16:9 image.

Don’t forget about this one, dear readers: you’ll likely be seeing it touted as “coming soon” by the rumor mill a few months down the line.

(via: WMPoweruser and NAK Phone Designs, images courtesy of NAK)