Just started using
LinkedIn as a business networking tool. I have already found it useful in finding old contacts that I have fallen out of touch with. I think the model is very neat in that you can only browse people that are in your network, ie. a friend of a friend of a friend (6 degrees of seperation). I have worked my traditional network in the past as little a possible because I find it to be rather intrusive. I think the LinkedIn model is much less intrusive and allows you to find people yourself and make a pointed request to a single person. This is in contrast to calling everyone in your network and asking "Hey do you know anyone who...?". We'll see if the powers that be at LinkedIn can make the business model work and turn a profit.