What makes a Watchmen cover?

" If you're a fan, it's like a lost cover. That's what it feels like, and that's what we were going for."

So says Zack Snyder of the Dave Gibbons poster currently doing the rounds.

Hurrm.

Don't get me wrong, I'm as buzzed as the next fan to see Gibbons drawing new Watchmen stuff, but this image is nothing like a Watchmen cover.

This...
...is like a Watchmen cover. The Gibbons poster is more like the opening panel of a missing issue. That's still exciting, but I worry slightly that the director of the Watchmen film doesn't know what makes a Watchmen cover a Watchmen cover.

I'm sure everything will be just fine in the end.