It has been said that 8 out of 10 job opportunities come from sources outside of those advertised. So it might be assumed that social networks, especially those centered around professional relationships like LinkedIn, would be ideal tools to find jobs and recruit new talent. Yet in the experiences of many job hunters, including myself, social networks like LinkedIn have yet to live up to this promise.

Social networks are a great tool for HR professionals and other job recruiters, making it easier than ever to search for employees with the right experience and skills.  Besides Facebook and Twitter, social networks such as LinkedIn, Plaxo, Brazen Careerist, and Xing have become popular places to post resumes and connect with like minded professionals.  Sometimes these professional networks have been known to generate new business opportunities, but for many job seekers these sites offer no greater a resource to find employment than Monster.com.

Part of the problem lies in how LinkedIn is used differently than other social networks.  Once you’ve finished setting up your profile with your resume and begin to connect with other professionals, there is little else to do on the site. While LinkedIn has 50 million registered accounts, less than half are active at least monthly (according to Quantcast).

Besides expanding your network of connections, LinkedIn confines interaction between its users to those who are already connected. Even with the integration of Twitter into the LinkedIn platform, interactions between members of a network are largely limited to interpersonal discussion.  By comparison to the open/public conversations that make Facebook and Twitter so popular, the end effect is to make discussion seem closed-off or private, further discouraging discovery and interaction between its members.

To be sure these social networks are becoming more popular as professionals look for meaningful ways to network online, or at least in a different (less personal) way than Facebook or Myspace promotes.  According to a Pew report the median age of a LinkedIn user is 39, significantly older than Twitter (31) or Facebook (33).  Perhaps this better explains why these communities interact differently; LinkedIn users might feel they are finished using the network once they’ve set up a profile, rather than integrating social media as part their everyday lives.

In my own job search, LinkedIn could be playing a pivotal role, although so far its just a supporting piece of the puzzle.  To be sure I’ve written recommendations for colleagues, networked in groups like #PRStudChat, and reached out through mutual connections, all of which have expanded my network.  So far LinkedIn has yet to land me any meaningful job opportunities, at least compared to board-based services like Mediabistro and Craigslist.  Until LinkedIn can leverage of their social network to create opportunities, especially for individual users, its potential will continue to yield diminishing returns on investment for organizations.