The page level social networking features have been disabled.
The main reasons are: they aren't really used - there has been little change in the number of clicks for each one for over 6 months and they dramatically slow down the page, increasing loading time which in turn has an effect on Google's SEO ranking.
Individual posts can still be shared by clicking on the Share link in the bottom right of each post.
Of course, any page or thread can still be shared manually on Twitter, Facebook or G+.