I'll tell ya what, if I was an employer these days, and things have changed from what the old fogeys are still trying to enforce, the first thing I'd do is an exact phrase search for the person's name in Google. Yup, that's the first thing. Oh, I'll use a few other terms in that query to refine my search and make sure I've found the right person. And, this only applies to specific industries. Not everyone can be found online, yet!
Political Activities? Wow! You mean to tell me if I find someone who is a practicing evangelist in a particular movement that goes against my government's way of life that I can't use that as a determination in hiring candidates? Bull#*$!
If you are in an industry where employers have quick access to your online profiles from social networking sites, you better be on the ball. If you are not, those profiles may be the death of your career objectives. And, if you piss someone off in your online travels, you'll have that page to contend with too. :(