I guess I have never thought of how the implementation of technologies would require an entirely new body of laws and precautions. Least of all would I suspect that adults would fall victim to the extent of requiring legal action. I mean, I remember the woman who made a false Myspace account to torment a girl on behalf of her daughter (Read about it here, the Megan Meier case). But adults using a website to post their harassment publicly just seems stupid. It would be like a murderer posting a picture of the murder weapon on Facebook.
I know I am a horrible person, and the first thing that comes to my mind is “You are going to get caught. Harass people more intelligently!”
Interestingly, this article doesn’t really suggest approaching this any differently than any other case of defamation of character or harassment. Simply don’t engage, keep everything on record, and contact the authorities.