Posting something about your employer without being anonymous is just plain stupid!
Depends on your employer. I post stuff about my employer all the time, under a slashdot username that is the same as my corporate LDAP username, and have gotten kudos for it. I've also gotten a couple of calls from legal, asking me to be careful about commenting on legal issues, but the attorneys apologized effusively for doing so, and pointed out that they recognized I was being careful but just want to reiterate that it was important.
But my employer is particularly open-minded, and particularly confident in its employees' judgement. You need to understand your context, and YMMV.