It’s Stanley Kubrick taking a smoke break with members of the cast of 2001: A Space Odyssey, in the pit on the moon where the first monolith is found. (Click on the image for a larger version.) From a collection of publicity stills for the film at a blog called Stanley Kubrick Deserving of Worship, which is like a Wikileaks for Kubrickiana.
[via Daring Fireball]