Facebook's amended Platform Policies for app developers regarding the use of "LIKES". Specifically, the Platform Policies now state "only incentivize a person to log into your app, like your app's Page, enter a promotion on your app's Page, or check-in at a place. Don't incentivize other actions. Effective November 5th, 2014, you may no longer incentivize people to like your app's Page."
In making this change, Facebook took issue with the core marketing practice of "LIKE-gating" - where access to an app or Page was conditioned upon "LIKING" the app/page. In Facebook's view, offering points, rewards or other incentives (including sweepstakes/contest entries) in exchange for "LIKING" an app/page and thereby unlocking content corrupted the integrity of use of the "LIKE" function. While not entirely clear, the new Platform Policies could also perhaps mean that entry in a sweepstakes/contest can no longer be affected by "LIKING" a post on a Facebook page or content in an app.
In addition, Facebook Personal Timelines and friend connections cannot be used to administer promotions. By way of example, the Platform Policies now prohibit programs where persons share a link to watch an entire video or invite 10 friends to use an app and thereby earn 50 free message points. In both cases, the content is made available to the user as a direct incentive for taking the prescribed action. However, if framed somewhat differently, Facebook would deem the latter activation to be in accordance with its Platform Policies: it is permissible to invite 10 friends to use the app and earn 50 free message points for every friend that accepts! Here, the incentive has apparently been "neutralized" as the receipt of the message points is conditioned upon the action of a third party.
The bottom line is that Facebook users cannot be required to "LIKE" an entity's Facebook page in order to unlock a sweepstakes/contest entry form. And, absent clarification from Facebook, tying sweepstakes/contest entry to "LIKING" a post or other content on an app/page may be problematic as well.