I think the pictures you've posted are both irrelevant - we sit in front of it, not behind it.
Speaking of which, who cares if it's thinner considering it's a desktop, not a laptop? What's the advantage to it being thinner, which Steve Jobs made a big deal out of yesterday? Compare the dimensions of the old vs. new iMacs:
20 inch:
Old 18.6" (H) x 19.4" (W) x 7.4" (D)
New 18.5" (H) x 19.1" (W) x 7.4" (D)
24 inch:
Old 20.6" (H) x 22.6" (W) x 8.1" (D)
New 20.5" (H) x 22.4" (W) x 8.1" (D)
The new ones are only a tiny bit smaller sitting in front of you, but takes up exactly the same amount of space depthwise from the front of the screen to the rear of the base. So much for being thinner. Why not reduce the chin instead, which many people clearly wanted, and the monitor wouldn't sit so high up especially on the 24"? Putting a black border to make the chin less pronounced isn't going to do it.
I would've liked to see a new form factor. Other than what's inside, I found the "redesigned" iMac disappointing.