blog job

My good friend advised me to be careful about blogging. Apparently people have lost their jobs due to their blogs. I wont write about my job...I already spend too many hours on the job, why would I want to spend my leisure hours talking about it?
I would write about my friends but now I worry that I might run the risk of losing them due to blogging.
I thought that blogging gave me an avenue to complain anonymously...now I need to think of the consequences here too!