E-mails and egos: "Justin Kruger, PhD, and his colleague Nicholas Epley, PhD, of the University of Chicago, have published research that helps explain why electronic misunderstandings occur so frequently. In a study in the December Journal of Personality and Social Psychology (Vol. 89, No. 5, pages 925-936), they find that people overestimate both their ability to convey their intended tone-be it sarcastic, serious or funny-when they send an e-mail, as well as their ability to correctly interpret the tone of messages others send to them."
A good read, and definitely something to keep in mind.