Many speculative fiction works have languages that depend to a great deal on the postures of the people communicating. Some examples are the language of the Adem in Patrick Rothfuss' The Wise Man's Fears and the language of the Khai in Daniel Abraham's Long Price Quartet.
Are there any such languages in the real world?
EDIT:To be clear, the common thread in both the languages is that the gestures are a formal part of the language. The words have lesser amounts of tone in them, and each sentence is supposed to be accompanied by a gesture. There are gestures which are very subtle, like 'polite but adamant refusal'. Also, it's expected for people to reply with gestures instead of small sentences etc.