The mobile feature, like the Web browser version, allows users to repost a friend's photos and links. The button is located at the bottom of a post next to the "like" and "comment" tabs, and users can add text before sharing a post.
Facebook and Twitter are both popular in their own right, but they've also started incorporating features that make them more similar. Twitter has been testing out "like" and star buttons to potentially replace the "favorite" tool the service has used for years. And Facebook's news feed has been compared to Twitter's stream of tweets.
As TechCrunch noted in an earlier post about the news, the share button for mobile shouldn't come as a big surprise. The site said that a Facebook manager commented during a talk a couple months ago that the company builds products its employees want to use, and a share button is one of those features.