If they were doing what we did, then they're really just talking about having a pool of 8 PS3 devkits available for rendering movies. Sure you could do it all with 1, but time is money.
We have a tool called the movie maker, that takes a scene in Maya, builds it as game data, renders it using the game engine, and then captures the output. It doesn't run at full frame rate, but like any offline renderer, draws, then captures a frame at a time. We then take those frames, and compress into an mpeg video stream.
We did this primarily to capture scenes that were either too complex to implement in real time (because our in-game cinematics tools sucked), or that didn't fit into the memory available on a retail unit. They are rendered using real game assets though, so that when you cut into them from the game and back, you can't see the joins. Well, unless you know what you're looking for. Like mpeg artifacts, or that the player character doesn't have the DLC costume on.