Social networking sites are not always condusive to making a good impression in the workplace. Employees, and prospective employees, have been finding this out the hard way over the past couple of years. Companies should be careful about social networking sites and how their employees use them, especially at work. Likewise, employees should be careful to groom their internet reputation.
http://blogs.bnet.co.uk/sterling-performance/2008/09/19/are-social-networking-sites-a-liability-at-work/