It looks like this E3 will be a major one for Sony and Nintendo- according to the floorplans revealed for the show space, both companies have massive showfloor space booked, dwarfing all others by a considerable margin.
Sony wins with 43,500 square feet of space booked. Nintendo has 32,400 square feet booked. No one else comes close- albeit many third parties have respectable showings, including Activision, EA, Ubisoft, Bethesda, and Warner Bros. Microsoft has 17,412 square feet, which is about as big as the showfloor space for those third parties.
Japanese third parties put in a pretty decent showing too, with Square Enix, Bandai Namco, and Capcom leading the pack there. Take Two Interactive has a smaller showfloor space than any of them, but it does tie with Sega, Atlus, and XSEED.
All in all, it sounds like Sony and Nintendo have a lot of things they want to show us. The question now is exactly what those things may be…