Quite true. They either employ infrared or lasers in a matrix config. I have two 4' large screen panels here at my office that overlay onto a plasma display. The software then allows me to write on the "notepad" and by touching an icon, I can then have my incursive or printed writing converted into any type of font in MS Word. Over time the software learns my writing style to more accurately interpret my words. Simply hit save document and it gets dumped into a folder or it can be sent over a network to a copy machine for mass duplication!! I can even annotate over web pages. Slick but very expensive!
AMX is a company that pioneers touch screen displays in a variety of sizes.