tbeta
Tbeta screenshot
The Beta, tbeta for short, is a open source/cross-platform solution for computer vision and multi-touch sensing. It takes an video input stream and outputs tracking data (e.g. coordinates and blob size) and touch events (e.g. finger down, moved and released) that are used in building multi-touch applications. tbeta can interface with various web cameras and video devices as well as connect to various TUIO/OSC enabled applications and supports many multi-touch lighting techniques including: FTIR, DI, DSI, and LLP with expansion planned for the future (custom modules/filters).
Touchlib
What is Touchlib?
Touchlib is a library for creating multi-touch interaction surfaces. It handles tracking blobs of infrared light, and sends your programs these multi-touch events, such as ‘finger down’, ‘finger moved’, and ‘finger released’. It includes a configuration app and a few demos to get you started, and will interace with most types of webcams and video capture devices. It currently works only under Windows but efforts are being made to port it to other platforms.
I just posted the developers explanation about the two main community cores from the Nuigroup for dealing with the “low-level” multi-touch aspects that I am going to be working on the GSOC 2009 
