LinkedIn has been accused of giving ad networks information that allowed them to follow users around the Internet with tracking cookies. The plaintiff is seeking class action status. Here is a copy of the LinkedIn Complaint and a copy of an article discussing the suit here. No responsive motion or pleading has been filed yet.
As an aside, if true, such a relationship would likely lead to liability for the 3rd parties that received and used the information because they would be data controllers that did not receive consent for collecting or processing user information.