I found this as I was catching up on my RSS feeds this morning. Dan Shawbel of Mashable! has an awesome post about how "Personal Branding Can Save You From Getting Fired."

I talked about this in my presentation to Regina Cassell's class a
couple weeks ago. By establishing a web presence (that you keep
updated) that promotes yourself as an expert on a given topic, your
marketability (and job security) is enhanced.

Shawbel makes several other points that are worth your time. Really,
you are shooting yourself in the foot if you aren't developing your web
presence.

Also, I highly recommend the Mashable! site. Grab the RSS feed and check in often.