The big problem with the LinkedIn API is that the ToS are pretty harrowing.
Who knows what they'll do to you if you succeed in using their (extremely valuable) data set: http://www.readwriteweb.com/archives/linkedin_platform_pros_...
Who knows what they'll do to you if you succeed in using their (extremely valuable) data set: http://www.readwriteweb.com/archives/linkedin_platform_pros_...
Plus, they have all sorts of bans on scraping, etc. They say users own their own data, but if their users use any tools to try to get their data, they block the tools....
It's too bad, because there are a lot of great things that could be built.