Regarding Stair Dismount (and potentially other Dismounts), demos and other stuff:

These two games (SPiN, Zen Bound) are our first step in testing the Maemo market. If the sales are reasonably better than the cost of porting, then it's obvious that bringing more games over is worth it. But currently we have no clue if a sufficient number of N900 owners is willing to pay for games. I guess we'll learn

Zen Bound will have a demo version.