If I were to somehow announce the location of every ship in the US Navy, the Navy would do two things about it. One, they would shoot me in the face until I was unable to repeat such a feat. Two, they would move every ship in the fleet to somewhere else. Why? Because knowledge is power.
The first step to defeating a ship, after all, is knowing where it is. After that, defeating it is a mere engineering problem. Puncture it enough, and down it goes. For this reason alone, the locations of such things are a dead-serious secret.
Of course, this is a much harder task now adays, since most people my generation and younger are used to Twitter and blogging, and revealing their location to the world at large at all times. And the more it is emphasized to them how secret their task is, the more they're tempted to think, "Well, now I gotta tell my friends. Secret mission, awesome!"
Unfortunately for them, it's not just their friends who are listening. Recently, a congressman had to be rapidly evacuated from a speaking engagement in Iraq because he just had to tell Twitter first. Ba'athist forces were listening and very nearly assassinated him.
I do not envy those working in Operational Security now. In the past, you just had to watch people's conversations and phone calls, but now you have to watch email, twitter, blogs, and a dozen other data sources. Sounds like a real headache.
I'd also like to tell the navy at this point that I have no idea how many ships it has, nor where they are, and ask that they please not destroy my house.
However, I'm going to assume that my readers are mostly not military. (Most Americans are not -- military is financed by taxes, and no civilians would mean no taxes.) What does this mean for you? Simply put: When you post things to the internet, people are watching. Your boss. Your friends. Your enemies. It gets to be like a small town, where everyone knows everything about you, and if they're nice, they might overlook a few indiscretions. (Still, you'd be a fool to rely on the kindness of strangers.) I can't how many times I've seen in the news where police catch a suspect because they posted details of a crime they committed onto Twitter, Facebook, or the like, and the police just show up with a printout and remind them that (drunk driving, bank robbing, face punching, insert as appropriate) isn't legal, please come with them.