Multi-Touch Interaction Research

"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."

http://mrl.nyu.edu/~jhan/ftirtouch/