There are some leaked screenshots on allgamesbeta.com. The pictures indeed look like id tech 5 and showing a post apocalyptic scenario.

id software let go 30 people in january (after rage release). a week after content popped up on artists profile websites. Including the websites of Thao Le (pics) and Mick Gordon (music).

Downloads: 170 pics, screenshots, assets, models, 4 mp3s
Filesource: doom3.ru

UPDATE: (Matt Hooper via twitter)
"Those images have nothing to do with what you're gonna see in Doom4. When we officially show things you'll see awesome."