The Marcom Blog points out that - if you are a blogger - you are actually creating one, and it can come back to bite you:

I have a friend that works at a large retail chain in the PR department. For the most part their company is very low on the radar in blogs. Recently though when I did a search in Technorati for the company name I came across a blog post from a teenager who had just started working there. In his post he detailed the training program and videos they watched as part of orientation. His comments were not very flattering.

He doesn’t work there anymore.

This is the way it's going to be - there's a small window right now where (some) hiring managers aren't that net savvy, so you can "get away" with saying whatever you want on a blog. That window is narrowing all the time though - I wouldn't be at all surprised to see past blog posts of mine being brought up if I were in a job search mode (I'm not :) ).

Maybe it would be a good idea to post one of those WWII vintage "Loose Lips Sink Ships" posters next to the keyboard :)

Update: Dana VanDen Heuvel has some good related points. I have a small comment on one one of the points:

Most people have never dealt with the media, and the media are only getting more savvy - everyone in your company should know how to deflect media inquiries and handle themselves in front of the media

The thing to keep in mind is - anyone can be a member of the media now. Say you attend a trade show, and - after a talk (or during it), you make a few comments. Do you have any idea whether you'll be quoted on someone's blog? I actually have people (not that often, but I expect to see more of it) ask me not to blog things - i.e., they want to stay off the record.