Guess what I'm doing...researching an article about it right now with Dr. Pennebaker.
http://homepage.psy.utexas.edu/homepage/faculty/pennebaker/home2000/jwphome.htmHis book "The Secret Life of Pronouns" was a great read.
And another one of my friends, Dr. Narayanan is researching similarly:
http://33bits.org/2009/01/15/de-anonymizing-the-internet/