Cutting Through points to Beyond bullets, which talks about research by Virginie Van Wassenhove, concerning the importance of visual communication:

In an age of online this and virtual that, it's nice to hear a little news about the value of a face-to-face. What about webcasting you say? According to Virginie,

"If visual movements lag (instead of naturally preceding) the auditory signal by as little as 50 to 100 milliseconds, the benefit of having visual speech is already diminished."

The average webcam hasn't quite reduced lag by that much, so while you're waiting for technology to catch up, the next time you have a face-to-face, pay attention to the visual speech you see, and how much it contributes to the auditory speech you hear. You just might find that you can understand quite a bit by reading someone's lips, not to mention the rest of their face.