Just announced not so long ago...
Engadget
Basically it has a 4.3" screen, 8mp camera with dual LED flash, 720p video and runs Android... more info to come I am sure!
HTC is also announcing pre-cached maps = no more data required for maps! Wow! Wonderful stuff and definitely stealing Nokia's Ovi Maps' thunder.
Update:
Desire HD:
1 GHz processor
Android 2.2 (Froyo) with HTC Sense
Internal phone storage: 1.5 GB
RAM: 768 MB
123 x 68 x 11.8 mm (4.84 x 2.68 x 0.46 inches)
164 grams (5.78 ounces) with battery
4.3-inch LCD touch screen with 480 x 800 resolution
8.0 megapixel color camera with auto focus and 2x LED flashlight
720p HD video recording
1230mah battery