A lab at the University of Ontario Institute of Technology and a lab at the University of Waterloo have been collaborating on a multi-touch library for Processing.
It is called the Simple Multi-Touch (SMT) Toolkit and has been in active development since the summer of 2011.
Its aim is to simplify multi-touch development. It is great for prototypes and research projects, but can also be used for more intense development.
Our toolkit supports Windows, Mac and Linux.
On the Processing website and in its IDE, it is under the category I/O.