p.3 They talk about where they see opportunities for tangibles:
... The only one of these that I like is #4. The other three seem to be coming from the wrong mindset. They paint these objects as little computers that communicate back and forth over a protocol. But messaging has to be one of many ways to think about how tangibles relate to each other. For example, two lightbulbs that grow brighter as they are brought closer together... are they communicating? I don't know, it just seems weird to focus so hard on communication.
No.4 is good though... objects can definitely be more expressive and this is suitably vague that it doesn't restrict my imagination.