Saying something in the chat room would certainly count as permanent, for the purposes of libel.
Journalists are told that *anything* committed to any medium can count: even if you scrawl 'Got the barstewards!" on the margin of a proof for a story that exposes some nastiness, you're leaving yourself open. Certainly, when emotions are running high in the office because we've got some juicy story we (well, some of us!) take particular care to keep our emails to each other on the subject studiously neutral.
I always have a little scene playing in the back of my mind whenever I'm writing: there's a hard-faced lawyer holding up a piece of paper -- Exhibit A, m'lud -- in court, and on it are the words I'm currently spewing out. That counts for Pprune, the various other online places I hang out, the news input screen at work and anything other than private email to one other person on matters not due for publication under any circumstances. Even then, I'm reticent.
That's not just for libel, but for any of the various other areas in which I dabble where the law might take an interest. I don't think I've upset anyone enough to have such an interest taken in me, but you just never know.
Friends of mine certainly have -- one pal wrote a major piece about a very litigious individual for a well-known magazine, and had to endure a four-hour no-coffee grilling by the publication's lawyers prior to print
(they congratulated him afterwards: he's an exceptional chap). The same guy has had the works before, with his flat turned over and nothing taken and other chilling happenings.
Don't believe such things don't happen, and don't believe there isn't a place for paranoia when dealing with the powerful.
R