I've given it something like five years to click and I'm still missing something. It's just not a fun web application to use. Twitter, Facebook, Stack Overflow, Quora and many others do a better job at the tasks LinkedIn half-heartedly attempts. If I want to connect with someone I don't know, I send them an email. The Rube Goldberg business where a chain of connections passes you around always felt weird and imposing to me.
At this point I feel like a cow at the feedlot, and LinkedIn sells me to staffing professionals.
Entirely willing to be put onto the right path, I'm just not seeing it right now.
edit: The score for jobs I've gotten through social sites:
LinkedIn: 0
Facebook: 0
Twitter: 2