I've seen it done right in a work environment -- the last company I worked for had an in-house Jabber server on the grounds that going up to someone's desk is extremely interrupty, email is formal and slow, and they'd like to have something in between -- but I can certainly see it being used for cowardice, drama, and all the other <sarcasm>wonderful</sarcasm> reasons it gets used in the non-work world, too.