
Facebook Sharecount is the name of this new service inspired, obviously, by Tweetmeme ReTweetbutton, but with a somewhat different functionality: it displays the number of shares and on hover the total number of clicks for those shares, displaying the Facebook logo when 0 shares.
Facebook Sharecount can be installed using JavaSctipt or through a Wordpress plug-in.
You can see it live in this post. To see how it works exactly, go ahead and share this post on Facebook :-)
Update: this doesn't seem to work very well, it's not even auto extracting the post title. I'll try adding it manually...