Facebook’s new “like” button release adjusts it’s functionality to that of a Share button. Now if you hit the like button your profile wall will include the full story and image. Prior to this new release if a user hit a “like” button it would merely be a link showing in your recent activity. The change should increase traffic to third part/publisher sites. Hence, in turn more people will adopt the Facebook like buttons, which is ultimately good for Facebook.
According to Josh Constine of Inside Facebook the Share button is often displayed amongst a set of other buttons for Twitter, Digg, bookmarking, and email, but Facebook would rather have its own real estate opposed to being lost amongst the competition. Now that Facebook has given the Like button almost a year to prove its worth, third-parties would probably implement a Like button if they could no longer use the Share button, granting Facebook this improved placement.
The phase out of the Share button is evident in Facebook’s documentation. The “Facebook Share” result shown when searching for “Share” on the developers site directs to the Like button documentation page.