Apoc has confirmed (Official EA Forums) that EA will be showing off C&C3 at E3. Here is what he said:
We will be at E3 with more than just an amazing kick [ass] incredible 360 trailer. We're working on a full blown out 1st official trailer for the game, and we will be having a special presentation at E3 which I expect you'll be hearing the press talk about quite a bit during the show.
If you're going, i'm the short 5" 5 guy riding around the E3 floor on a scooter (wink)
It looks like we have something to really look forward to at E3. As much as I would love to go, ticket prices are insanely high. Looks like I will have to watch the video on the internet with everybody else later that day.