I just witnessed what the difference between LinkedIn and Facebook is all about. I searched for Guy Kawasaki in both networks. In LinkedIn he has 225 contacts and I am 3 hops from him. On facebook he has 2774 friends and I am 6 hops from him. I guess that’s it’s not only the number of connections that you have, but rather type of people that you have as contacts.
Would be interesting to see how LinkedIn would work as a platform that would allow developing applications