One of the great challenges of knowledge work is in understanding how to integrate virtual tools into the oftentimes tricky realm of human communication and relationships. We take for granted that the constantly evolving toolset available to us is ultimately helpful to our productivity and ability to complete our day-to-day tasks. How did work ever get done without mobile phones and the constant stream of e-mail? But the techniques for binding it all together — the ways to manage our time and our attention in order to best take advantage of the digital without becoming a slave to it — are still largely undefined. How do we incorporate the oftentimes virtual, and sometimes real world interactions that now make up business and professional relationships? We may work far away from our colleagues, then have face-to-face meetings, then go back to working at a distance. Sometimes it feels like we've been thrust into the virtual world with no rules. Increasingly, it seems like it is the duty of knowledge workers to figure out just how we should relate to our digital workplace, and each other.

Within this chaotic sea of digital tools that we incorporate into our work lives, perhaps one of the more interesting ones is our professional social graph. With a virtual professional network, you can stay connected to business contacts over time, and potentially build these relationships for mutual benefit. The professional social graph is our virtual map of our career contacts and reflects our work lives through the relationships we've developed. LinkedIn, of course, is the most popular and prominent business network in the US, with roughly 90 million members, although others like Viadeo and XING have significant traction internationally.