Multi-touching sensing is an innovative concept best seen most recently in the movie, Minority Report. People at NYU appear to have come up with amazing results in this space. Check it out and play the video on the top right to the end. Just amazing.
Here is what they say about multi-touch sensing. "While touch sensing is commonplace for single points of contact, multi-touch sensing enables a user to interact with a system with more than one finger at a time, as in chording and bi-manual operations. Such sensing devices are inherently also able to accommodate multiple users simultaneously, which is especially useful for larger interaction scenarios such as interactive walls and tabletops."