Ubisoft has announced Jam Sessions for the DS.  It is a guitar simulator similar to how guitar hero works.  It looks like it has a lot of potential.  Here are some of the details on the controls for the game:

Today, we alone are bringing you the news that in June, Ubisoft will release Jam Sessions, a game that turns your Nintendo DS portable into a handheld mini-guitar–you use the stylus, your finger or a guitar pick to strum the touch screen, selecting the desired notes (they’ve been digitally remastered from an actual acoustic guitar) using the D-pad and a shoulder button.

Sounds pretty cool to me—check the link for a video of the game in action.  Good song too!

Source: Newsweek