Over the past week the concept of ‘The Semantic Web‘ has made the jump from academic theory to fledgling reality. The launch on Friday of the first semantic search engine Wolfram Alpha has generated a lot of hype in the tech sphere. In addition to that big news, Google’s forthcoming semantic search solution, Google Squared, and Sir Tim Berners Lee’s Linked Data project have been getting press as the excitement for this brave new world of search grows.

The idea that we will soon be able to take data from all over web and pull it into a form that’s useful to us is highly seductive. However, there’s a dark side to semantic search that leads me to hesitate in welcoming our new Web 3.0 overlords. While this new era will allow you to easily generate data about anything you care to research, someone else could just as easily be researching you.

I’ve never been particularly worried about the data I put online about myself. I always hold something back and after all, it would take a lot of work for anyone to find and piece together that data into something that they could use in any harmful way against me. Now the semantic web is suddenly on our doorstep and it will suddenly be a whole lot easier for people to find all sorts of information about anyone within seconds.

Do you share your listening habits online? Maybe you occasionally publish your location to something like Brightkite or Google Latitude? Maybe you share your Amazon shopping list with the world? You almost certainly mention tiny details about your life on a regular basis online via services like Twitter. By pulling these tiny bits of information together, the semantic search engine of the future will be a stalker and conman’s dream. Suddenly it will be possible to ask: “Where does John Smith live and work and what are his hobbies? What are his children called?”

Imagine the ways that information could be used against you by someone that meant you harm. Suddenly information that used to take weeks to build up could be collated in seconds.

With issues like ID cards and Deep Packet Inspection in the news in the UK, the idea that ‘Big Brother is watching us’ is at the forefront of people’s minds. In the age of the Semantic Web, ‘Little Brother’ could be just as much of a threat.