If I could get one point across to people who have not used LinkedIn or are signed up but have not started building there network it would be “even if you don’t know why you should build your network today, you will have a head start if you figure it out tomorrow”. Eric Mariacher echoes this point in his post, along with some other thoughts.
Perhaps you don’t need to network today, but what about tomorrow? How do you know that you can’t have any better opportunity than today?