Linkedin has changed its default privacy settings and can now use your picture and name in their advertisements.
To change this default behavior and turning the option off that Linkedin can use your personal information do the following:
Go to settings (located under your name) click on the account tab.
You will see the option Manage Social Advertising click it and remove the check mark.
Update: 12 aug 2011
It seems Linkedin has listened to its members and changed the setting so that every member opts-out of inclusion from all social ads by default.
See Privacy, Advertising, and Putting Members First
So, Linkedin will change how these types of social ads look, from this: