There were several vendors showing their large interactive lcd and plasma screens. All worked using an infra-red detection frame around the outside of the screen. They were strapped on to the apparatus itself or appeared to be part of it.
Plasma screens are glass covered and so these were more in evidence. One vendor had an lcd screen (with its plastic front) which had another surface made of glass in front. This was not as easy to see from the side as the plasma screens without any separate surface.
These screens, particularly in the larger version, were expensive. I talked to the Head of a school who explained the project that they had had on this in Cumbria using these in the Early Years. The school did not have one per classroom but used this with children since the system was very easy to interact with.
Perhaps not quite there yet (in terms of price and ease of use) so my earlier appeal for manufacturers to get on with solving this problem still applies.