nintendo will have to show a lot tommorow or be ridiculed in the press. ms and sony totally unloaded all their info so nintendo needs to show everything they have, otherwise the buzz will be monopolized by ps3 and xbox 360 until the next big event and by then it will be harder for nintendo to get their foot in the door.
i expect nintendo to try to equal sony in terms of the amount they show... i think they'll show the console, a bunch of trailers and if they have it, they might even show something in-game (maybe mario). i think there is a chance that internal nintendo development might be pretty far along on some of their next gen games. I do fear that the system will be weaker than the other two in terms of specs though, because of the reported size, but if the revolutionary gimmic is really really cool, they might be able to get away with it. if thats the case, they should go ahead and spill the beans.
edit// i think the really important thing is for nintendo to beat microsoft...