I signed up with LinkedIn a long time ago, and tend to not pay much attention to it until I receive an invite, which inevitably gets me to browse link trees finding other contacts I may know. Thus far, my only business use for LinkedIn has been routing requests from individuals who want to contact others at Adobe (and Macromedia previously). I have tried to use LinkedIn to find contacts that I needed, but thus far those attempts were rather unsuccessful.
What I have not really figured out is who to accept link requests from. I have dozens of link requests from people I have never heard of, and many more from names that are familiar but whom I really don't know well enough to recommend, route requests to, or anything else. So, do I add these as links? My gut feel is not, but I don't decline them either (I did once, way back when, and apparently really insulted someone), so they just sit there as pending invites which is neither here nor there.
Either way, this recent post by Guy Kawasaki (and the comments posted) has prompted me to take another look at LinkedIn.