I only joined linked in a month or two back, haven't actually bothered much with it (haven't even added anyone to it yet) but I still seem to get a few contractors offering positions every now and again (not that I'm looking to switch jobs, work is quite handily close considering I'm in the middle of nowhere - we get one bus an hour, and I can't drive)
I've heard that foreign agencies are using LinkedIn to keep tabs on people with security clearances. Not really surprising though. It's a great open source way to get the "big picture".
