It may be a little hard to make out, but what you see there is concept art for different versions of the whole sack family that Media Molecule said was originally supposed to accompany our beloved Sack Boy. The company's talk at GDC was full of similar revelations from the development of LittleBigPlanet and you can find a couple more just after the break.
For instance, did you know that before the Pop-it, items were managed through a traditional inventory screen? It apparently took a few iterations before the team settled on an inventory that the player always carries with them.
Oh, and were you aware that the game once had bosses like this massive mechanical dinosaur?