Chances are you or someone you know is on Facebook, MySpace, or LinkedIn. Google yourself and you'll probably see a LinkedIn or Facebook biography. Potential employers and recruiters will see the same information during the hiring process.
When I prepare for a deposition I always do basic Internet research on a witness. It's probably a safe assumption that business prospects and competitors are doing the same thing. This type of screening is cheap, quick, and turns up all sorts of information from previous employment, education, civic involvement, and even your time in the neighborhood fun run.
The reality is the Internet now documents all aspects of our lives. An Internet biography is being updated in real time for each of us and has a wide range of content. Social networking tools are wonderful in theory, but they contribute to our Internet biography.
There is no reason to quit updating your Facebook status. But as with anything in writing, assume it will be seen by all, not just your Facebook friends. Welcome to the reality of Web 2.0.