On August 8th, 2014 Facebook announced that they are banning like gates on fan pages starting on November 5th, 2014.
So no more promos asking you to “like” a page to enter to win something.
“You must not incentivize people to use social plugins or to like a Page. This includes offering rewards, or gating apps or app content based on whether or not a person has liked a Page. It remains acceptable to incentivize people to login to your app, checkin at a place or enter a promotion on your app’s Page. To ensure quality connections and help businesses reach the people who matter to them, we want people to like Pages because they want to connect and hear from the business, not because of artificial incentives. We believe this update will benefit people and advertisers alike.”