I've seen the tutorials of how to build a multitouch-scren on the web, where's your part in this?
Shortly after these videos (not the TED-Talk, though) came out, I started to build a multi-touch screen using the presented technique myself, without reading the paper, tough. At the time I started, there were no manuals or ready-made software, so I made my own. Nowadays, with the multi-touch hype you'll be able to find software for all kinds of systems and interfaces; as these libraries were released however, I still liked my own better, mostly for the higher quality tracking and lower latency.
Did you invent this?!
No. Just read the article on Wikipedia about it and see the long history of it.
But Apple's holding the patents!
These don't apply to the cheap optical technique used in this project; or they're too trivial; or don't apply in europe.