Have you noticed how Google AdWords shows you directly targeted advertising on LinkedIn? Something that goes far beyond AdWord's normal capabilities of targeting. For example, I always see recruitment ads for a local Java consultancy house known for their agile process expertise, no matter what I'm doing on LinkedIn. It certainly doesn't have anything to do with the page the ads are on, nor is it related to search keywords. As a proof, take the case of searching for a farming expert in Nepal: I'm still seeing ads for that consultancy, Scrum process management tools, and SOA testing. If there's a connection to my activities, I'm at loss what it is.

However, I know exactly what they ARE targeting. My own profile, which mentions all those things, and more. LinkedIn and Google are not advertising to my stated intent (what I'm searching for), or the page content (as an AdSense customer might expect), but myself and what I've told the service about me.