I've written about the need to understand how "public" our thoughts, ideas and conversations are these days. Hundreds, no thousands of others have issued the same warnings. I think most people still figure we're talking about what you post online, but if you think about it, it's really not the case.

There's a powerful lesson in this today from Sheila Scarborough on the Every Dot Connects blog. Sheila writes:

PR guy Peter Shankman was riding the train to some business-related destination when another man sat across from him, pulled out a cell phone and said "Apologies in advance, I talk a lot."

Insert grimace here, right? Immediately don iPod/noise-canceling headphones, and rue the advent of technology, right?

Shankman went further.

He could hear from the man's constant chatter that he was conducting sensitive business on the phone, so Shankman decided that an object lesson was in order.

With a warning tweet out to his Twitter stream, Shankman turned his laptop around, faced it towards Mr. Oblivious Babbling Businessman and proceeded to livestream the guy on Yahoo LIVE.

Cool? No, not really. One of those cases where being a jerk to the jerk doesn't make you any less of one...but I get the frustration and the desire to "teach a lesson."

I remember a few months back when I was sitting in Panera Bread and overheard a conversation about search engine marketing at the table next to me. A search marketing consultant was trying to sell his services to a local business owner and was throwing out pretty much ever antiquated bit of bad SEO advice I've ever heard. Frustrated, but not wanting to make him look bad to the client, I ended up Twittering a great deal of the conversation.

Of course in retrospect, I realized it was quite possible either the consultant or the client could conceivably have been following me on Twitter and have read my posts. Ultimately, it could have even affected the consultants ability to get the contract.

All because technology makes it possible for our conversations to be broadcast without our knowledge.

What the story really reminds me of though is the need for constant reputation monitoring. If you read through Sheila's full post, you'll find out something else interesting that happened:

When I logged on to Yahoo LIVE, about 50 people were listening to and watching Mr. Oblivious Babbling Businessman. They were researching madly and posting...

His name.

His company.

His LinkedIn profile, including an aside that he only had two connections.

His ZoomInfo page.

His work phone number.

You see, it's one thing to be online monitoring for your name because you are blogging or engaging in social media and expect people to be talking about you. It's a whole other thing to have something posted based on an overheard conversation. For his own sake, I'd hope this fellow runs the occasional Google search for himself and finds out he's being discussed and in what context before his business colleagues do.

Nothing is private anymore. Emails can be forwarded, social sites are spidered, conversations are Twittered and actions are videoed by cell and uploaded to YouTube. You can't stop it, but you can consider it and you can keep an eye out for it.

You can also remember the old adage of never doing anything you wouldn't want to see on the front page of the New York Times. After all, it's a social media world out there.