Further driving the point home, Bungie's Joseph Staten has posted more details on the authenticity of the new Gamecenter screenshots. In addition to this confirmation, he also gives some details on the origins of those shots:

As for the new shots' authenticity. Since I took them, I can tell you they're real. Even better, we were on a really tight deadline for GameCenter, and I had to take these shots in half an hour. In other words, these (like all our shots to date) aren't concept images.

And there you have it, The Word of Bungie has been passed down. Hope that helps settle down the authenticity debate which, amazingly, managed to continue even after the first round of confirmation appeared...

• Forum: New HALO Shots