Nintendo hasn't said anything new even on Skyward Sword. They have only given us a few screenshots. To me, that tells me they don't have time to make a trailer, for they are putting top priority on the game. I'm assuming they will not make a demo available for Wii Shop, since then they would have to get the demo game, modify it, then release it on Wii Shop. Doesn't sound like a lot of work, but I don't think Nintendo would do that. They're more likely to put their full focus on making the entire game rather than a small demo.