Plus, there’s more: Publishers installing Facebook share buttons can also get data back related to how many times that link has been shared, how many users have hit the thumbs-up “like” button or commented on shared versions of the story on Facebook, and how many people have clicked back to it through Facebook.

These Facebook “share” buttons had existed before, and the company said that more than 2 billion pieces of content are shared per week. But this is the first time that the counter and analytics have been available.

A post on the Facebook developer blog explains: “Anyone can add the Share button to their website with little to no technical experience, and style the button from a variety of options.” Accessing the analytics however, requires a bit more coding know-how.

This could spell bad news for Digg, as Facebook’s significantly bigger and more mainstream audience could make it a far more appealing choice for site owners that would prefer to display one prominent sharing button rather than two. As for Twitter, it doesn’t actually own the app that powers the “retweet” buttons. A move like this from Facebook, however, could push it to think a bit harder about a partnership or acquisition–or hasten progress on that “retweet API” it has in the works.

Related speculation: When are we going to see a “most-shared” ranking from Facebook? That’s when Digg’s execs would really have to start sweating.