Okay, as I noted above, they have officially released this information. At Comic-Con LEGO will officially reveal the set Batman: The Riddler Chase, featuring the Flash. This set will come out next January and will cost US$29.99. Also, the LEGO booth will feature life-size sculptures of Superman and Iron Man.
IMO, the fans are far more fun than corporate-driven displays and giveaways. I'm sure we'll see some MOCs, and I know there's going to be a panel on LEGO art sponsored by BrickJournal (I'll cover this on ArtisticBricks), and you always see lots of different costumes. Here are a couple of fan costumes from Philly Comic Con and Niagra Falls Comic Con earlier this year.