From the article: "Microsoft's privacy protection feature in Internet Explorer, known as P3P, is impractical to comply with while providing modern web functionality such as cookie-based features, Google said Monday in response to an accusation from Microsoft that Google had bypassed privacy protections in Internet Explorer…. IE by default blocks third-party cookies unless a site presents to the browser a P3P Compact Policy Statement describing how the site will use the cookie and pledging not to track the user. Third party cookies are those dropped by domains other than the one in the user's browser address bar." Read more
