if nintendo does have one BIG secret they want to reveal, my guess is that its going to be on the last day of e3.
it would be the biggest cocktease ever if they did.
its like "okay big press confrence, what suprises should we let out...hmm...nothing really, Wiiconnect24 isnt as special as the BIG secret, so let give them that, lets not talk about price yet either, just to have a bomb to drop later....lets be nice, show off mario without talking about it beforehand and let the crowd roar...."
next few days show a few suprise games...
last day "we're so glad to see all of you having so much fun enjoying Wii and the games offered to you. your reactions please us to no end and we're sure Wii is going to be a huge success. By the way......BIG SECRET!"
and then the internet explodes.