One of my personal rules on blogging has always been not to comment on things that irritate me at work, not least because I'm blogging under my own name and the parties in question could find said comments. To be fair, these last few years I've worked with a great batch of people (at two different jobs), but there are always small and occasionally large things that raise one's hackles.
I think this rule is why my blogging has always ever been so light. If only because my daily job, like everyone's, encompasses so much of my daily experience. Not commenting on it puts a huge chunk of my thoughts and feelings out of play.
On a related note, people who say disparaging things about co-workers on Facebook not only violate my one rule in an even baser fashion, they also violate their mother with their clear lack of upbringing.