Bashiok made an informative post about a feature we’ve seen (or not) in a number of screenshots so far; invisible characters. Someone asked about, with only the NPC corpse and the beasts visible. Bashiok said:
It’s an option in our editor to hide various elements, and in the case of these shots the player was hidden to show off the environments and monsters.
And yes those are lootable corpses.
He also pointed to a number of screens where this is in evidence. ( in our recent caption this contest.) This sort of thing is a standard part of the toolkit designers build into their games for development. They can also elect to hide the interface or character, zoom the camera in odd ways, turn on or off monster AI, enable god mode, warp to any area in the game, and more. You see these sorts of commands in use at gaming shows, so they can demo and talk at the same time without dying, show off different areas of the game very quickly, etc. They’re removed before the game is released.