How people get into the E3 Expo. *please read on?

I know that to get into E3 one has to either work in the game industry or in the press that covers it, but as I was watching the E3 coverage on G4, IGN, etc. I keep seeing a lot of people in the background that don't look like either of those thing. For example I see extremely, for lack of better words, nerdy people that are like carrying around bookbags and are cheering for the cameras. I have determined that they are not journalists because, if they were press, they would have press badges and would be out doing their job( you know "press stuff"). I doubt they are developers or any of that sort; they just don't look like they would be because, like the journalists, they would be at their demo stations etc. So please Yahoo answers "Enlighten" me.