While I'm on the subject of touch input, I want to talk about Nintendo's DS.
I got my DS back in December '04 and have been fascinated by the many different application gestures they recognize, particularly in WarioWare: Touched! They use the mic, swirly spiral gestures, tapping, strokes, back-and-forth and more. What a wonderful idea for Touch training on a Tablet! Unfortunately, I didn't really push the idea and so I don't think that our new tutorials are anything like the minigames in WarioWare: Touched! They're more of the same "picture changes when you successfully perform task" type of thing.
I wonder what we could do to make the Pen/Touch training more enjoyable for users, to draw them into actually doing the training. Would making a very simple game a la Minesweeper or Solitaire, that specifically used the different input modalities be worthwhile?