This year, while Nintendo might not hold a typical pre-E3 conference they will be allowing fans to play some of the game demos at the same time that they're being shown off on the show floor. All you need to do is head on over to your nearest Best Buy and hope it's not too busy and you'll be able to try out and view some new games for the Wii U as they're being shown to the press at E3.
Nintendo has plans to show off their new Smash Bros., a 3D Mario game, a new Mario Kart, and more. Just don't expect to see every game on display at Best Buy that is being shown at E3.