Facebook is changing the way the Like button works. Until now clicking on a Like button resulted in a short notification in Recent Activity feed, but it will now generate a full story with a thumbnail, blurb and headline. This change effectively obsoletes the Share button and consolidates the functionality of the Like button.
Facebook is calling the change a test, indicating that it's waiting to see how the users and website owners respond before making it the only option. Still, the Share button is being de-emphasized.
Until now, there were three ways of interacting with a website using Facebook. The Share button posted an update on your wall, which showed up on your friends' News Feed.
This update contained captions from the link, images and comment from the user. It essentially automated the process of posting a link on Facebook.
The Like button, by default, without additional comments from the user, only generated a short entry in the Recent Activity feed and rarely ended up in the News Feeds of friends. However, it did add a subscription to the Facebook page of that site.
If the users added a comment, the link would be published as a full story, similar to sharing it.
Now, Facebook is testing an expanded Like button which generates a full story regardless if users comment or not. It works like the share button, but it also comes with a subscription.
From a publisher's point of view, the new Like button is more valuable than the simple share functionality. For Facebook, it generates more traffic since third-parties will be more likely to implement it.
It also makes it clearer for users what the Like button does. However, users have gotten used to the way the button functions now. Once they realize that the button now generates full stories, they may not like the change in behavior, especially since it's applied retroactively.