I was so happy when I saw it! GO NEXUS!
http://hoopload.com/profiles/blogs/nexus-one-spotted-in-the-event
http://hoopload.com/profiles/blogs/nexus-one-spotted-in-the-event
It's not a Desire. I have one right beside me. Look at the picture - the Desire doesn't have that curvature at the top of the screen.I saw the same episode the other night and thought exactly the same as you. I went as far to rewind and freeze frame it.
It was then that I noticed a slight difference between my Nexus One and the one on the screen. The ear piece has two LED's (one either side). Then I realised it was the Desire as that has indicator lights there. The other reason is the headphone socket is on the other side to ours on the shot as it pans out.
I have to agree that it isn't the Desire (just Google Imaged it) and the earpiece os totally different but there are definately two LED looking sections either side of the earpiece grill (ours doesnt have anything similar). The main difference is the headphone socket sits on the left on the unit (ours is on the right) as the guy is holding it, we see the underside of the phone.The IR proximity sensor might be picked up as a LED by the camera and turned visible - many cameras "see" some of the IR spectrum, unlike human eyes.
Judging by the picture - it doesn't look like Desire, it can be only Nexus.
Look closer on the both sides of the earpiece, when the phone is in direct strong light that will penetrate the screen tint. You'll see 2 "things" on the left side of the earpiece, and 1 "thing" on the right. The "thing" on the right you know - it's a charging LED, which is visible. The left one your eyes can't see - but cameras see it, as I pointed earlier, and it's a proximity sensor - blinking IR LED with IR receptor which measures reflected light....but there are definately two LED looking sections either side of the earpiece grill (ours doesnt have anything similar).
It always is so strange to me when I see someone in person with a Nexus One. You can tell it is immediately but it just shocks you given how rare they are compared to other smartphones.