I have actually been on the other side of this kind of situation where I wrote about a friend in my blog, rather than talking to her. It wasn't a PA way to get a message to her (she had long since stopped checking my blogs), it was a way for me to work through my own troubles and feelings regarding our failing relationship.
I think it really depends on whether or not you are or still are friended by the person. A few years ago, I had a situation (gee, a fandom friendship) that went very bad very quickly. I never ever used names in my LJ - I was very cautious about that. But, at the same time, I did try to figure out there what was going on, discussing it with others who I was (and still am) close to.
Unfortunately, the person I had the falling out with seemed to think nothing of reading my LJ to find fuel for her fire. Still does now and then, from what I understand. However, I told her back then - I hide nothing. If you want to come and be insulted for things that may or may not involve you, have fun. Leave me out of it. She was getting insulted at things that were not even about her, but not even fandom related! Some people, apparently, forget that there is life beyond fannish pursuits