The more i play with technology, the more i see the importance of paper.
When working on bidimensional visualization surfaces (that is 99% of the time), we use objects and spaces that are very similar to paper sheets. That is why providing the affordance of paper, especially in tabletop interfaces, guarantees a more natural interaction with objects.
But paper has also another, very important, feature: it is disposable.
Creativity needs freedom, and experimentation is made of many trials. Paper is a friend of prototypation and sketching, it is transportable and always-on. In general, every intermediate step in the production of an idea perfectly fits the temporary persistence of paper, while the digital domain is the right place for the final outcome.
Bridging the two domains is the challenge: digital pen and paper (like Anoto) is trying to give an answer, i expected many more products based on this cunning technology, but we are still at the beginning.
In my view interactive tables in general are one of the "pillars" for this bridge, an my research is heading also in this direction.