My wife and I both witnessed a craft over Seattle, WA on August 28, 2007, between 2:45- 2:47 AM. We were out on our balcony facing West viewing the lunar eclipse that was occurring at the same time. I had my Nikon D90 digital camera setup on a tripod and was snapping off photos of the eclipse. When my wife saw the craft 'gliding' nearly over head towards the west I watched it for a bit and then swung the camera over to snap three shots.
Since my camera was setup to photograph the moon nothing really came out in the pictures. However, they are high resolution pictures (over 3000 pixels) and someone with the proper imaging tools might be able to find the craft in these pictures.
What we saw was essentially the same thing in the photo you have: A black silhouette triangular craft with an array of circular lights. We think there were 11-13 lights.
We have many planes fly over head, including the Blue Angels during Sea Fair and of course planes coming in and out of Boeing Field and Sea-Tac.
What struck me is that my ears were waiting for the roar of this craft's engines as it flew past us. We did not hear a sound and it appeared to be gliding at a constant speed on a fix trajectory (no turns, just smooth gliding). Here is a computer sketch attached my wife made of what she saw. It literally flew over downtown Seattle heading West/SouthWest.
source and references:
Submitted to UFO Casebook
Archived UFO Articles and News Items, 2008
UFO Casebook Home Page