it's absolutely true. People are already being denied jobs and degrees for a stupid facebook post. We had a local newsreader who was fired for having posted a claim that he was audited by the IRS.

My rule of thumb for the internet

If the comment is linked to your real name or a real email, don't put anything online that you wouldn't say in a job interview. I have a couple of throwaways that aren't connected to my real name, and I am a bit more free to speak on those. The only places that are really free are places that don't keep records -- no sign ins, and the threads disappear after a time. Outside of that, just figure that someone would find it.