The Hot Librarian has a post entitled Legal Ramifications of Blogging about Work based on a BBC News article on the subject.
As a budding law student/eventual-lawyer, I'd like to think that law students and lawyers (in particular) would know better than to blog about specific incidents occurring at work. Besides the confidentiality issues, there's always defamation and the like not to mention random acts of firing on trumped-up charges based on questionable content. (That is, we're firing you for "x" although it's really becuase you posted blog entries saying the company/firm stinks like a rotting fish carcus laying out in the Georgian sun.)
By the way, a misconception I want to clear up briefly. The truth is not always a defense. In my Media & The Law class second year of law school I learned that one. About 90% of the time, yes, truth is a defense. However, where specific knowledge would render the revealed information defamatory notwithstanding its veracity, truth is not a defense. Example: "Margaret Jones is pregnant." Appears to be non-defamatory, right? However, suppose that Margaret Jones is a Sister at the local church. Suddenly the statement becomes defamatory based on this extra knowledge. I don't remember any other specifics for this point but I do remember that much (example included).
In any case, I don't actually have anything substantive to relate on the work-blogging topic. It's not something I ever anticipate pursuing, in either an anonymous or non-anonymous setting, and it's not something "smart" bloggers will undertake. Blogging about work in a controversial manner is rolling the dice. You hope nothing you say will come back and bite you in the ass, possibly ousting you from your job. Why are people surprised when it happens?
Perhaps the one thing I can comment on here is that blogging is starting to retain stronger ties to real-world influences and effects. As a blogger, this is certainly something you need to consciously remember every time you post. It's the reason I stopped posting about The Girl or, for that matter, any of the girls. (At one point I identified them by a random letter. I laugh at that now. And, for the record, "them" constitutes two women, I believe.) Those are definitely an example of something that could come around and hamstring me at a later date. That's not to say I won't do the same thing at a later time since, well, you know, no one ever said I was smart enough to take my own advice. And it makes for good blogging-fodder... as long as "she" doesn't read it...