We didn't see the new Doom that was shown exclusively to Quakecon attendees in Dallas this week. You probably didn't either. But all the people in a video shot by the folks at the unofficial Quakecon Forums did.
They just saw it minutes before this video was recorded, and they were pumped. Skip to 50 seconds to get to the reactions. A baby supposedly clapped for the first time... to the new Doom!
Language NSFW, not surprisingly.