It has been stated by scholars who study body language that 60 to 80% of human communication is through non-verbal communication, or body language.
In terms of animation, that adds some meaning as to why some animation communicates so well without dialogue and why we love, for example, French animation, or Japanese animation so much. See the post about Shane Acker's short film "9" (below), as a recent example of animation that communicates without dialogue.
Ian Lacey (Animation Resource Centre) always encourages his students, who seek to be character animators, to animate what the character is thinking.
Acting for Animators author, Ed Hooks, also describes it as essentially important.
The important communication is displayed through the character's body language.
The animation is particularly delicious when the dialogue was in contradiction to how the character was communicating non-verbally. It can drive a whole story in the opposite way to the characters' dialogue thus giving insight or unease to the audience. The animator is the one who controls it.
I think it is important for animation students to realise the importance of recognising non-verbal communication as a skill. Firstly, in terms of observation. Observation being: seeing + thinking about what you are seeing. And secondly in looking to thoughtfully apply techniques, such as: facial touching gestures, psychological gestures, line of action reversals, power centre shifts, meaningful symbolism to every opportunity in animating.
Hey, those things sound familiar don't they? Psychological Gestures, Line of Action, Power Centres, Meaningful Symbolism... they all relate to posing in story telling poses (click for a great resource .mov download from Keith Lango).
Many of you have probably already seen this video on body language (I'm sure Dan might like it for the music ;) ) ...
An interesting experiment for student animators is to search video sharing sites for video reference on body language. You will pick up some good ideas and maybe even someone at a nightclub.