Touchlib is a library for processing multi-touch interaction with a suitable multi-touch input surface. 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 interface with most types of webcams and video capture devices. It currently works only under Windows but can be compiled to work on linux as well. (i haven’t tested Touchlib’s functionality on linux for my self first hand so i can’t comment it its workings)
More info about Touchlib can be found here.
Download precompiled binarys of Touchlib Beta v2.0.
Alternatively you can download the source and compile it.