Social networking is everywhere – and not just on computers. Walk into a cinema, and it's right there in front of you – Facebook founder Mark Zuckerberg is the subject of Brian Singer's recent hit film "The Social Network". Pick up a magazine, and there he is again – Zuckerberg was also named Time Magazine's Person of the Year for 2010. For many of us, social networking may be little more than a distraction, but for others it is a way of life. And for others again, it's a way of business.

Certainly, it is possible to dismiss social networking as a virtual forum where adults get to keep in touch, share meaningless information and play games with each other. Many occasional Facebook participants will be left wondering why we should care what someone had for breakfast – or what they need to get to succeed in "Mafia Wars" (whatever they are). But like it, hate it or try to ignore it, there is no doubting that the likes of Facebook and, to a lesser extent, MySpace and Bebo have transformed communication and society. And it's possible that something like LinkedIn has, to some degree, transformed business. But has social networking transformed the business of recruitment?

"I would say that LinkedIn is a must-have for professionals," said career and outplacement expert Paul Mullan. "Two out of every three jobs are in the hidden jobs market (the market that is not advertised), and LinkedIn will help people to access a far wider network, providing themselves with visibility to people who they don't yet know. In fact, I would say that any company that is currently recruiting is integrating social media into their overall strategy."

Indeed, LinkedIn is now offering special training workshops to help people actively search for staff, and employers and recruiters can actively canvass for candidates through various "groups" and forums. Simultaneously, candidates can increase their own employability by using their LinkedIn page as an up-to-date, accessible and comprehensive on-line CV (anecdotally, many hiring managers may not look at a CV, but they will check out a LinkedIn page), thereby increasing their visibility and, by extension, their employability.

So there are advantages to this new technology. But equally it could be argued that certain facets of social networking have actually harmed people's chances of getting a job, because it's far easier for a prospective employer to find out about people's bizarre and unorthodox behaviour if they have their entire social life emblazoned across the World Wide Web.

"If I'm meeting someone and preparing them for a job interview, I will scour the internet on their behalf to see what I can find," said Eoghan McDermott, head of the Careers Clinic at The Communications Clinic. "It's so frequent that I get onto a person's Facebook page and see photos that have been put up without thinking – maybe with them naked, or with strangely rolled cigarettes. If a recruiter sees those, then the interview is over before the person has a chance to speak."

Indeed, anyone looking for a job should remember that their on-line lives are interchangeable with their professional lives. Even in the earliest days of the internet people could be undone by their online presences – after all, who wants to give a job to a person whose e-mail address is smirnoffandwhite@eircom.net? But these issues are hugely magnified by social networking sites, which can tell a potential employer so much about a person that they would ordinarily be trying to hide. And this is why anyone, whether a jobseeker or even an incumbent, should actively manage their social networks, and set their privacy settings to a high level. Because Big Brother is always watching.

"I believe that anything that you put into the internet should be done with an eye on the bigger picture," said McDermott. "It's the first place that people will go to find out what you've been up to."