A very well-thought and written article. LinkedIn is like a corporate party, where everyone is there, connected but there is no party indeed, just a crowd of faces hanging around. In that way it becomes just another resume service with some job board features through ads. They are trying hard to bring interactivity by small inventions like endorsements, recommendations and also sometimes mirroring similar interactions from Twitter, Facebook to LinkedIn. At the end of the day they are still selling premium membership to jobseekers, (ability to get) connections with inmails and services for headhunters and recruiters to digg into the pile of resumes.

I believe LinkedIn can achieve much more than that by creating an application store similar to Google's and Apple's. where 3rd party apps can be listed, featured and installed and billed in a recurring or per-request basis.

Through a LinkedIn app store, 3rd parties can bring a lot of innovative functionality to LinkedIn.