A few studies have shown that 80% of HR personnel will do searches for potential hires on the popular social sites such as FaceBook and Twitter. It is important for people who are actively or passively looking for new opportunities to be aware of this fact and take appropriate action.
A common strategy that many people take is to just make their profile completely private and visible to only those that they are friends with. While this does prevent the drunken and inappropriate photos from being viewed by recruiters, those recruiters are also going to assume that you have something to hide.
The best approach is to always monitor what your profile(s) say about you, not just to your friends but also employers that you don’t even know are looking. Leave some parts of your profile available to the public (not the really personal stuff like contact info) so that you can openly demonstrate your competence for handling social media. Social Media is becoming more and more important for people working for companies and many are looking for that specific skill. They need to know that the actions of employees won’t hurt the company.