It seems like Facebook has pulled the previously mentioned 'sacrifice your friends for a whopper' campaign from its site for 'privacy reasons' because the application 'facilitated activity that ran counter to user privacy by notifying people when a user removes a friend'.

233,906 friends were removed by 82,771 people in less than a week.

Could be a start of Facebook tightening up their rules for marketing within their site, especially if there is any app or widget that pulls in info from your friends.